21631057 has 8 divisors (see below), whose sum is σ = 24831936. Its totient is φ = 18457872.

The previous prime is 21631039. The next prime is 21631061. The reversal of 21631057 is 75013612.

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 21631057 - 2¹¹ = 21629009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21631007) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5218 + ... + 8395.

It is an arithmetic number, because the mean of its divisors is an integer number (3103992).

Almost surely, 2^21631057 is an apocalyptic number.

It is an amenable number.

21631057 is a deficient number, since it is larger than the sum of its proper divisors (3200879).

21631057 is a wasteful number, since it uses less digits than its factorization.

21631057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13847.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21631057 is about 4650.9200165129. The cubic root of 21631057 is about 278.6287418596.

Adding to 21631057 its reverse (75013612), we get a palindrome (96644669).

The spelling of 21631057 in words is "twenty-one million, six hundred thirty-one thousand, fifty-seven".