8721631 has 2 divisors, whose sum is σ = 8721632. Its totient is φ = 8721630.

The previous prime is 8721617. The next prime is 8721667. The reversal of 8721631 is 1361278.

8721631 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 8721631 - 2⁵ = 8721599 is a prime.

It is a super-2 number, since 2×8721631² = 152133694600322, which contains 22 as substring.

8721631 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 8721631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8722631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4360815 + 4360816.

It is an arithmetic number, because the mean of its divisors is an integer number (4360816).

Almost surely, 2^8721631 is an apocalyptic number.

8721631 is a deficient number, since it is larger than the sum of its proper divisors (1).

8721631 is an equidigital number, since it uses as much as digits as its factorization.

8721631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 28.

The square root of 8721631 is about 2953.2407622813. The cubic root of 8721631 is about 205.8413253229.

The spelling of 8721631 in words is "eight million, seven hundred twenty-one thousand, six hundred thirty-one".