645064019 has 4 divisors (see below), whose sum is σ = 645253440. Its totient is φ = 644874600.

The previous prime is 645063983. The next prime is 645064037. The reversal of 645064019 is 910460546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645064019 - 2²⁸ = 376628563 is a prime.

It is a super-2 number, since 2×645064019² = 832215177216864722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645064019.

It is not an unprimeable number, because it can be changed into a prime (645064619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89507 + ... + 96444.

It is an arithmetic number, because the mean of its divisors is an integer number (161313360).

Almost surely, 2^645064019 is an apocalyptic number.

645064019 is a deficient number, since it is larger than the sum of its proper divisors (189421).

645064019 is a wasteful number, since it uses less digits than its factorization.

645064019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189420.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 645064019 is about 25398.1105399595. The cubic root of 645064019 is about 864.0408444590.

The spelling of 645064019 in words is "six hundred forty-five million, sixty-four thousand, nineteen".