645654919 has 48 divisors (see below), whose sum is σ = 853106688. Its totient is φ = 483392448.

The previous prime is 645654907. The next prime is 645654929. The reversal of 645654919 is 919456546.

It is not a de Polignac number, because 645654919 - 2⁷ = 645654791 is a prime.

It is a super-2 number, since 2×645654919² = 833740548857793122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645654929) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1860504 + ... + 1860850.

It is an arithmetic number, because the mean of its divisors is an integer number (17773056).

Almost surely, 2^645654919 is an apocalyptic number.

645654919 is a deficient number, since it is larger than the sum of its proper divisors (207451769).

645654919 is a wasteful number, since it uses less digits than its factorization.

645654919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524 (or 517 counting only the distinct ones).

The product of its digits is 1166400, while the sum is 49.

The square root of 645654919 is about 25409.7406322851. The cubic root of 645654919 is about 864.3045939485.

The spelling of 645654919 in words is "six hundred forty-five million, six hundred fifty-four thousand, nine hundred nineteen".