645589690 has 32 divisors (see below), whose sum is σ = 1222606224. Its totient is φ = 245122560.

The previous prime is 645589667. The next prime is 645589709. The reversal of 645589690 is 96985546.

It can be written as a sum of positive squares in 8 ways, for example, as 456719641 + 188870049 = 21371^2 + 13743^2 .

It is a super-2 number, since 2×645589690² = 833572095668592200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6109 + ... + 36448.

Almost surely, 2^645589690 is an apocalyptic number.

645589690 is a deficient number, since it is larger than the sum of its proper divisors (577016534).

645589690 is a wasteful number, since it uses less digits than its factorization.

645589690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42642.

The product of its (nonzero) digits is 2332800, while the sum is 52.

The square root of 645589690 is about 25408.4570566573. The cubic root of 645589690 is about 864.2754867472.

The spelling of 645589690 in words is "six hundred forty-five million, five hundred eighty-nine thousand, six hundred ninety".