731566021 has 2 divisors, whose sum is σ = 731566022. Its totient is φ = 731566020.

The previous prime is 731566013. The next prime is 731566079. The reversal of 731566021 is 120665137.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 706815396 + 24750625 = 26586^2 + 4975^2 .

It is a cyclic number.

It is not a de Polignac number, because 731566021 - 2³ = 731566013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (731566091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 365783010 + 365783011.

It is an arithmetic number, because the mean of its divisors is an integer number (365783011).

Almost surely, 2^731566021 is an apocalyptic number.

It is an amenable number.

731566021 is a deficient number, since it is larger than the sum of its proper divisors (1).

731566021 is an equidigital number, since it uses as much as digits as its factorization.

731566021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 731566021 is about 27047.4771651627. The cubic root of 731566021 is about 901.0547391543.

The spelling of 731566021 in words is "seven hundred thirty-one million, five hundred sixty-six thousand, twenty-one".