20987613 has 16 divisors (see below), whose sum is σ = 31852800. Its totient is φ = 13649760.

The previous prime is 20987611. The next prime is 20987627. The reversal of 20987613 is 31678902.

It is not a de Polignac number, because 20987613 - 2¹ = 20987611 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20987611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8373 + ... + 10586.

It is an arithmetic number, because the mean of its divisors is an integer number (1990800).

Almost surely, 2^20987613 is an apocalyptic number.

It is an amenable number.

20987613 is a deficient number, since it is larger than the sum of its proper divisors (10865187).

20987613 is a wasteful number, since it uses less digits than its factorization.

20987613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19009 (or 19003 counting only the distinct ones).

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

The square root of 20987613 is about 4581.2239630911. The cubic root of 20987613 is about 275.8381612645.

The spelling of 20987613 in words is "twenty million, nine hundred eighty-seven thousand, six hundred thirteen".