21288790 has 16 divisors (see below), whose sum is σ = 38673360. Its totient is φ = 8436960.

The previous prime is 21288779. The next prime is 21288829. The reversal of 21288790 is 9788212.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 8676 + ... + 10855.

It is an arithmetic number, because the mean of its divisors is an integer number (2417085).

Almost surely, 2^21288790 is an apocalyptic number.

21288790 is a deficient number, since it is larger than the sum of its proper divisors (17384570).

21288790 is a wasteful number, since it uses less digits than its factorization.

21288790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19647.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 21288790 is about 4613.9776765823. The cubic root of 21288790 is about 277.1513463483.

The spelling of 21288790 in words is "twenty-one million, two hundred eighty-eight thousand, seven hundred ninety".