645695020 has 48 divisors (see below), whose sum is σ = 1450014048. Its totient is φ = 240665600.

The previous prime is 645694981. The next prime is 645695023. The reversal of 645695020 is 20596546.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (645695023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24939 + ... + 43741.

It is an arithmetic number, because the mean of its divisors is an integer number (30208626).

Almost surely, 2^645695020 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 645695020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (725007024).

645695020 is an abundant number, since it is smaller than the sum of its proper divisors (804319028).

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

645695020 is a wasteful number, since it uses less digits than its factorization.

645695020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18930 (or 18928 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 645695020 is about 25410.5297071903. The cubic root of 645695020 is about 864.3224872844.

The spelling of 645695020 in words is "six hundred forty-five million, six hundred ninety-five thousand, twenty".