20641631 has 2 divisors, whose sum is σ = 20641632. Its totient is φ = 20641630.

The previous prime is 20641627. The next prime is 20641633. The reversal of 20641631 is 13614602.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20641631 - 2² = 20641627 is a prime.

It is a super-2 number, since 2×20641631² = 852153860680322, which contains 22 as substring.

Together with 20641633, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20641597 and 20641606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20641633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320815 + 10320816.

It is an arithmetic number, because the mean of its divisors is an integer number (10320816).

Almost surely, 2^20641631 is an apocalyptic number.

20641631 is a deficient number, since it is larger than the sum of its proper divisors (1).

20641631 is an equidigital number, since it uses as much as digits as its factorization.

20641631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 20641631 is about 4543.3061750228. The cubic root of 20641631 is about 274.3140191860.

The spelling of 20641631 in words is "twenty million, six hundred forty-one thousand, six hundred thirty-one".