20981637 has 24 divisors (see below), whose sum is σ = 31549440. Its totient is φ = 13422240.

The previous prime is 20981617. The next prime is 20981641. The reversal of 20981637 is 73618902.

It is not a de Polignac number, because 20981637 - 2⁶ = 20981573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20981617) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43564 + ... + 44042.

It is an arithmetic number, because the mean of its divisors is an integer number (1314560).

Almost surely, 2^20981637 is an apocalyptic number.

It is an amenable number.

20981637 is a deficient number, since it is larger than the sum of its proper divisors (10567803).

20981637 is a wasteful number, since it uses less digits than its factorization.

20981637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 673 (or 670 counting only the distinct ones).

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

The square root of 20981637 is about 4580.5716892109. The cubic root of 20981637 is about 275.8119781165.

The spelling of 20981637 in words is "twenty million, nine hundred eighty-one thousand, six hundred thirty-seven".