645232581 has 16 divisors (see below), whose sum is σ = 1092457600. Its totient is φ = 368704224.

The previous prime is 645232573. The next prime is 645232597. The reversal of 645232581 is 185232546.

645232581 is a `hidden beast` number, since 6 + 45 + 2 + 32 + 581 = 666.

It is not a de Polignac number, because 645232581 - 2³ = 645232573 is a prime.

It is a super-2 number, since 2×645232581² = 832650167167843122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645232561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1706776 + ... + 1707153.

It is an arithmetic number, because the mean of its divisors is an integer number (68278600).

Almost surely, 2^645232581 is an apocalyptic number.

It is an amenable number.

645232581 is a deficient number, since it is larger than the sum of its proper divisors (447225019).

645232581 is a wasteful number, since it uses less digits than its factorization.

645232581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3413945 (or 3413939 counting only the distinct ones).

The product of its digits is 57600, while the sum is 36.

The square root of 645232581 is about 25401.4287196606. The cubic root of 645232581 is about 864.1160988855.

The spelling of 645232581 in words is "six hundred forty-five million, two hundred thirty-two thousand, five hundred eighty-one".