20986631 has 2 divisors, whose sum is σ = 20986632. Its totient is φ = 20986630.

The previous prime is 20986613. The next prime is 20986639. The reversal of 20986631 is 13668902.

Together with previous prime (20986613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20986631 - 2¹⁴ = 20970247 is a prime.

It is a super-2 number, since 2×20986631² = 880877361460322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20986591 and 20986600.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20986639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493315 + 10493316.

It is an arithmetic number, because the mean of its divisors is an integer number (10493316).

Almost surely, 2^20986631 is an apocalyptic number.

20986631 is a deficient number, since it is larger than the sum of its proper divisors (1).

20986631 is an equidigital number, since it uses as much as digits as its factorization.

20986631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 20986631 is about 4581.1167852392. The cubic root of 20986631 is about 275.8338590871.

The spelling of 20986631 in words is "twenty million, nine hundred eighty-six thousand, six hundred thirty-one".