21631214057 has 4 divisors (see below), whose sum is σ = 22377118020. Its totient is φ = 20885310096.

The previous prime is 21631214051. The next prime is 21631214083. The reversal of 21631214057 is 75041213612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15450738601 + 6180475456 = 124301^2 + 78616^2 .

It is a cyclic number.

It is not a de Polignac number, because 21631214057 - 2¹⁰ = 21631213033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21631214051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 372951938 + ... + 372951995.

It is an arithmetic number, because the mean of its divisors is an integer number (5594279505).

Almost surely, 2^21631214057 is an apocalyptic number.

It is an amenable number.

21631214057 is a deficient number, since it is larger than the sum of its proper divisors (745903963).

21631214057 is an equidigital number, since it uses as much as digits as its factorization.

21631214057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 745903962.

The product of its (nonzero) digits is 10080, while the sum is 32.

Adding to 21631214057 its reverse (75041213612), we get a palindrome (96672427669).

The spelling of 21631214057 in words is "twenty-one billion, six hundred thirty-one million, two hundred fourteen thousand, fifty-seven".