20631989 has 12 divisors (see below), whose sum is σ = 25045344. Its totient is φ = 16914744.

The previous prime is 20631983. The next prime is 20631991. The reversal of 20631989 is 98913602.

It is not a de Polignac number, because 20631989 - 2⁴ = 20631973 is a prime.

It is a super-2 number, since 2×20631989² = 851357940192242, which contains 22 as substring.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20631983) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8027 + ... + 10280.

It is an arithmetic number, because the mean of its divisors is an integer number (2087112).

Almost surely, 2^20631989 is an apocalyptic number.

It is an amenable number.

20631989 is a deficient number, since it is larger than the sum of its proper divisors (4413355).

20631989 is a wasteful number, since it uses less digits than its factorization.

20631989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18344 (or 18337 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20631989 is about 4542.2449295475. The cubic root of 20631989 is about 274.2713005379.

The spelling of 20631989 in words is "twenty million, six hundred thirty-one thousand, nine hundred eighty-nine".