20903987 has 16 divisors (see below), whose sum is σ = 23697408. Its totient is φ = 18295200.

The previous prime is 20903969. The next prime is 20903989. The reversal of 20903987 is 78930902.

It is a cyclic number.

It is not a de Polignac number, because 20903987 - 2⁸ = 20903731 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20903987.

It is not an unprimeable number, because it can be changed into a prime (20903989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44918 + ... + 45380.

It is an arithmetic number, because the mean of its divisors is an integer number (1481088).

Almost surely, 2^20903987 is an apocalyptic number.

20903987 is a deficient number, since it is larger than the sum of its proper divisors (2793421).

20903987 is a wasteful number, since it uses less digits than its factorization.

20903987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 20903987 is about 4572.0878163045. The cubic root of 20903987 is about 275.4713107873.

The spelling of 20903987 in words is "twenty million, nine hundred three thousand, nine hundred eighty-seven".