20631421 has 6 divisors (see below), whose sum is σ = 21916730. Its totient is φ = 19417536.

The previous prime is 20631409. The next prime is 20631433. The reversal of 20631421 is 12413602.

It is an interprime number because it is at equal distance from previous prime (20631409) and next prime (20631433).

It can be written as a sum of positive squares in 3 ways, for example, as 15405625 + 5225796 = 3925^2 + 2286^2 .

It is not a de Polignac number, because 20631421 - 2⁵ = 20631389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20631491) 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, 35406 + ... + 35983.

Almost surely, 2^20631421 is an apocalyptic number.

It is an amenable number.

20631421 is a deficient number, since it is larger than the sum of its proper divisors (1285309).

20631421 is an equidigital number, since it uses as much as digits as its factorization.

20631421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71423 (or 71406 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 20631421 is about 4542.1824049679. The cubic root of 20631421 is about 274.2687836126.

The spelling of 20631421 in words is "twenty million, six hundred thirty-one thousand, four hundred twenty-one".