21631055 has 16 divisors (see below), whose sum is σ = 27661824. Its totient is φ = 16181760.

The previous prime is 21631039. The next prime is 21631061. The reversal of 21631055 is 55013612.

It is not a de Polignac number, because 21631055 - 2⁴ = 21631039 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21631055.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13970 + ... + 15440.

It is an arithmetic number, because the mean of its divisors is an integer number (1728864).

Almost surely, 2^21631055 is an apocalyptic number.

21631055 is a deficient number, since it is larger than the sum of its proper divisors (6030769).

21631055 is a wasteful number, since it uses less digits than its factorization.

21631055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1666.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21631055 is about 4650.9198015016. The cubic root of 21631055 is about 278.6287332723.

Adding to 21631055 its reverse (55013612), we get a palindrome (76644667).

The spelling of 21631055 in words is "twenty-one million, six hundred thirty-one thousand, fifty-five".