20731631 has 4 divisors (see below), whose sum is σ = 20777064. Its totient is φ = 20686200.

The previous prime is 20731589. The next prime is 20731637. The reversal of 20731631 is 13613702.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20731631 - 2⁶ = 20731567 is a prime.

It is a super-2 number, since 2×20731631² = 859601047840322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20731597 and 20731606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20731637) 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, 22025 + ... + 22946.

It is an arithmetic number, because the mean of its divisors is an integer number (5194266).

Almost surely, 2^20731631 is an apocalyptic number.

20731631 is a deficient number, since it is larger than the sum of its proper divisors (45433).

20731631 is an equidigital number, since it uses as much as digits as its factorization.

20731631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45432.

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 20731631 is about 4553.2000834578. The cubic root of 20731631 is about 274.7121218864.

The spelling of 20731631 in words is "twenty million, seven hundred thirty-one thousand, six hundred thirty-one".