64643531 has 2 divisors, whose sum is σ = 64643532. Its totient is φ = 64643530.

The previous prime is 64643519. The next prime is 64643539. The reversal of 64643531 is 13534646.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64643531 is a prime.

It is a super-2 number, since 2×64643531² = 8357572200295922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (64643539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32321765 + 32321766.

It is an arithmetic number, because the mean of its divisors is an integer number (32321766).

Almost surely, 2^64643531 is an apocalyptic number.

64643531 is a deficient number, since it is larger than the sum of its proper divisors (1).

64643531 is an equidigital number, since it uses as much as digits as its factorization.

64643531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 32.

The square root of 64643531 is about 8040.1200861679. The cubic root of 64643531 is about 401.3362208972.

The spelling of 64643531 in words is "sixty-four million, six hundred forty-three thousand, five hundred thirty-one".