20390885 has 8 divisors (see below), whose sum is σ = 25130616. Its totient is φ = 15871680.

The previous prime is 20390873. The next prime is 20390891. The reversal of 20390885 is 58809302.

It can be written as a sum of positive squares in 4 ways, for example, as 2362369 + 18028516 = 1537^2 + 4246^2 .

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

It is not a de Polignac number, because 20390885 - 2¹⁸ = 20128741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54926 + ... + 55295.

It is an arithmetic number, because the mean of its divisors is an integer number (3141327).

Almost surely, 2^20390885 is an apocalyptic number.

It is an amenable number.

20390885 is a deficient number, since it is larger than the sum of its proper divisors (4739731).

20390885 is a wasteful number, since it uses less digits than its factorization.

20390885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110263.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 20390885 is about 4515.6267560550. The cubic root of 20390885 is about 273.1987398359.

The spelling of 20390885 in words is "twenty million, three hundred ninety thousand, eight hundred eighty-five".