20631987 has 12 divisors (see below), whose sum is σ = 29841240. Its totient is φ = 13736448.

The previous prime is 20631983. The next prime is 20631991. The reversal of 20631987 is 78913602.

It is an interprime number because it is at equal distance from previous prime (20631983) and next prime (20631991).

It is not a de Polignac number, because 20631987 - 2² = 20631983 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

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, 11868 + ... + 13494.

It is an arithmetic number, because the mean of its divisors is an integer number (2486770).

Almost surely, 2^20631987 is an apocalyptic number.

20631987 is a deficient number, since it is larger than the sum of its proper divisors (9209253).

20631987 is a wasteful number, since it uses less digits than its factorization.

20631987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3042 (or 3039 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 20631987 is about 4542.2447093920. The cubic root of 20631987 is about 274.2712916756.

The spelling of 20631987 in words is "twenty million, six hundred thirty-one thousand, nine hundred eighty-seven".