64531581 has 32 divisors (see below), whose sum is σ = 94711680. Its totient is φ = 38937600.

The previous prime is 64531573. The next prime is 64531591. The reversal of 64531581 is 18513546.

It is not a de Polignac number, because 64531581 - 2³ = 64531573 is a prime.

It is a super-2 number, since 2×64531581² = 8328649892719122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64531501) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123601 + ... + 124121.

It is an arithmetic number, because the mean of its divisors is an integer number (2959740).

Almost surely, 2^64531581 is an apocalyptic number.

It is an amenable number.

64531581 is a deficient number, since it is larger than the sum of its proper divisors (30180099).

64531581 is a wasteful number, since it uses less digits than its factorization.

64531581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 637.

The product of its digits is 14400, while the sum is 33.

The square root of 64531581 is about 8033.1551086731. The cubic root of 64531581 is about 401.1044083160.

The spelling of 64531581 in words is "sixty-four million, five hundred thirty-one thousand, five hundred eighty-one".