21131137621 has 6 divisors (see below), whose sum is σ = 23226787766. Its totient is φ = 19210125000.

The previous prime is 21131137619. The next prime is 21131137627. The reversal of 21131137621 is 12673113112.

It can be written as a sum of positive squares in only one way, i.e., 20559258225 + 571879396 = 143385^2 + 23914^2 .

It is not a de Polignac number, because 21131137621 - 2¹ = 21131137619 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 21131137621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131137627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87318630 + ... + 87318871.

Almost surely, 2^21131137621 is an apocalyptic number.

It is an amenable number.

21131137621 is a deficient number, since it is larger than the sum of its proper divisors (2095650145).

21131137621 is a wasteful number, since it uses less digits than its factorization.

21131137621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174637523 (or 174637512 counting only the distinct ones).

The product of its digits is 1512, while the sum is 28.

The spelling of 21131137621 in words is "twenty-one billion, one hundred thirty-one million, one hundred thirty-seven thousand, six hundred twenty-one".