645440136 has 96 divisors (see below), whose sum is σ = 1821865920. Its totient is φ = 190270080.

The previous prime is 645440129. The next prime is 645440141. The reversal of 645440136 is 631044546.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 645440097 and 645440106.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 104445 + ... + 110451.

It is an arithmetic number, because the mean of its divisors is an integer number (18977770).

Almost surely, 2^645440136 is an apocalyptic number.

645440136 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 645440136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (910932960).

645440136 is an abundant number, since it is smaller than the sum of its proper divisors (1176425784).

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

645440136 is a wasteful number, since it uses less digits than its factorization.

645440136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6075 (or 6060 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 33.

The square root of 645440136 is about 25405.5138897051. The cubic root of 645440136 is about 864.2087437161.

The spelling of 645440136 in words is "six hundred forty-five million, four hundred forty thousand, one hundred thirty-six".