20890985 has 4 divisors (see below), whose sum is σ = 25069188. Its totient is φ = 16712784.

The previous prime is 20890979. The next prime is 20891009. The reversal of 20890985 is 58909802.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5438224 + 15452761 = 2332^2 + 3931^2 .

It is a cyclic number.

It is not a de Polignac number, because 20890985 - 2²² = 16696681 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2089094 + ... + 2089103.

It is an arithmetic number, because the mean of its divisors is an integer number (6267297).

Almost surely, 2^20890985 is an apocalyptic number.

It is an amenable number.

20890985 is a deficient number, since it is larger than the sum of its proper divisors (4178203).

20890985 is an equidigital number, since it uses as much as digits as its factorization.

20890985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4178202.

The product of its (nonzero) digits is 51840, while the sum is 41.

The square root of 20890985 is about 4570.6657064371. The cubic root of 20890985 is about 275.4141857865.

The spelling of 20890985 in words is "twenty million, eight hundred ninety thousand, nine hundred eighty-five".