64400556 has 72 divisors (see below), whose sum is σ = 174953520. Its totient is φ = 18360320.

The previous prime is 64400551. The next prime is 64400587. The reversal of 64400556 is 65500446.

It is a super-2 number, since 2×64400556² = 8294863226218272, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (64400551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23380 + ... + 25988.

It is an arithmetic number, because the mean of its divisors is an integer number (2429910).

Almost surely, 2^64400556 is an apocalyptic number.

64400556 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64400556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87476760).

64400556 is an abundant number, since it is smaller than the sum of its proper divisors (110552964).

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

64400556 is a wasteful number, since it uses less digits than its factorization.

64400556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2655 (or 2642 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 30.

The square root of 64400556 is about 8024.9957009334. The cubic root of 64400556 is about 400.8327567540.

The spelling of 64400556 in words is "sixty-four million, four hundred thousand, five hundred fifty-six".