721515131 has 2 divisors, whose sum is σ = 721515132. Its totient is φ = 721515130.

The previous prime is 721515127. The next prime is 721515143. The reversal of 721515131 is 131515127.

721515131 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 721515131 - 2² = 721515127 is a prime.

It is a super-2 number, since 2×721515131² = 1041168168523894322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 721515131.

It is not a weakly prime, because it can be changed into another prime (721515121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360757565 + 360757566.

It is an arithmetic number, because the mean of its divisors is an integer number (360757566).

Almost surely, 2^721515131 is an apocalyptic number.

721515131 is a deficient number, since it is larger than the sum of its proper divisors (1).

721515131 is an equidigital number, since it uses as much as digits as its factorization.

721515131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1050, while the sum is 26.

The square root of 721515131 is about 26861.0336919486. The cubic root of 721515131 is about 896.9092046848.

The spelling of 721515131 in words is "seven hundred twenty-one million, five hundred fifteen thousand, one hundred thirty-one".