21611631 has 8 divisors (see below), whose sum is σ = 28874160. Its totient is φ = 14378432.

The previous prime is 21611621. The next prime is 21611669. The reversal of 21611631 is 13611612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21611631 - 2⁶ = 21611567 is a prime.

It is a super-3 number, since 3×21611631³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21611598 and 21611607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5550 + ... + 8603.

It is an arithmetic number, because the mean of its divisors is an integer number (3609270).

Almost surely, 2^21611631 is an apocalyptic number.

21611631 is a deficient number, since it is larger than the sum of its proper divisors (7262529).

21611631 is a wasteful number, since it uses less digits than its factorization.

21611631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14665.

The product of its digits is 216, while the sum is 21.

The square root of 21611631 is about 4648.8311434166. The cubic root of 21611631 is about 278.5453083803.

The spelling of 21611631 in words is "twenty-one million, six hundred eleven thousand, six hundred thirty-one".