645523566 has 32 divisors (see below), whose sum is σ = 1352021760. Its totient is φ = 205079424.

The previous prime is 645523559. The next prime is 645523573. The reversal of 645523566 is 665325546.

It is an interprime number because it is at equal distance from previous prime (645523559) and next prime (645523573).

It is a super-2 number, since 2×645523566² = 833401348522712712, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30790 + ... + 47318.

It is an arithmetic number, because the mean of its divisors is an integer number (42250680).

Almost surely, 2^645523566 is an apocalyptic number.

645523566 is an abundant number, since it is smaller than the sum of its proper divisors (706498194).

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

645523566 is a wasteful number, since it uses less digits than its factorization.

645523566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16840.

The product of its digits is 648000, while the sum is 42.

The square root of 645523566 is about 25407.1558030410. The cubic root of 645523566 is about 864.2459781680.

The spelling of 645523566 in words is "six hundred forty-five million, five hundred twenty-three thousand, five hundred sixty-six".