20987137 has 8 divisors (see below), whose sum is σ = 21225600. Its totient is φ = 20750400.

The previous prime is 20987119. The next prime is 20987143. The reversal of 20987137 is 73178902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20987137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20987096 and 20987105.

It is not an unprimeable number, because it can be changed into a prime (20987237) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52137 + ... + 52537.

It is an arithmetic number, because the mean of its divisors is an integer number (2653200).

Almost surely, 2^20987137 is an apocalyptic number.

It is an amenable number.

20987137 is a deficient number, since it is larger than the sum of its proper divisors (238463).

20987137 is a wasteful number, since it uses less digits than its factorization.

20987137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 863.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 20987137 is about 4581.1720116145. The cubic root of 20987137 is about 275.8360759081.

The spelling of 20987137 in words is "twenty million, nine hundred eighty-seven thousand, one hundred thirty-seven".