6440620536 has 96 divisors (see below), whose sum is σ = 19959114240. Its totient is φ = 1837975104.

The previous prime is 6440620531. The next prime is 6440620553. The reversal of 6440620536 is 6350260446.

6440620536 is a `hidden beast` number, since 6 + 440 + 6 + 205 + 3 + 6 = 666.

It is a super-3 number, since 3×6440620536³ (a number of 30 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 6440620536.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6440620531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 439845 + ... + 454251.

It is an arithmetic number, because the mean of its divisors is an integer number (207907440).

Almost surely, 2^6440620536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6440620536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9979557120).

6440620536 is an abundant number, since it is smaller than the sum of its proper divisors (13518493704).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6440620536 is a wasteful number, since it uses less digits than its factorization.

6440620536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15313 (or 15306 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The square root of 6440620536 is about 80253.4767844983. The cubic root of 6440620536 is about 1860.5552487290. Note that the first 3 decimals are identical.

The spelling of 6440620536 in words is "six billion, four hundred forty million, six hundred twenty thousand, five hundred thirty-six".