645918812 has 36 divisors (see below), whose sum is σ = 1419961200. Its totient is φ = 251655360.

The previous prime is 645918811. The next prime is 645918839. The reversal of 645918812 is 218819546.

It is a super-2 number, since 2×645918812² = 834422223390982688, which contains 22 as substring.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645918811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91937 + ... + 98712.

Almost surely, 2^645918812 is an apocalyptic number.

It is an amenable number.

645918812 is an abundant number, since it is smaller than the sum of its proper divisors (774042388).

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

645918812 is a wasteful number, since it uses less digits than its factorization.

645918812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190682 (or 190669 counting only the distinct ones).

The product of its digits is 138240, while the sum is 44.

The square root of 645918812 is about 25414.9328545247. The cubic root of 645918812 is about 864.4223311784.

The spelling of 645918812 in words is "six hundred forty-five million, nine hundred eighteen thousand, eight hundred twelve".