21790605 has 16 divisors (see below), whose sum is σ = 34966080. Its totient is φ = 11587968.

The previous prime is 21790597. The next prime is 21790609. The reversal of 21790605 is 50609712.

It is not a de Polignac number, because 21790605 - 2³ = 21790597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790609) 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, 3769 + ... + 7601.

It is an arithmetic number, because the mean of its divisors is an integer number (2185380).

Almost surely, 2^21790605 is an apocalyptic number.

It is an amenable number.

21790605 is a deficient number, since it is larger than the sum of its proper divisors (13175475).

21790605 is a wasteful number, since it uses less digits than its factorization.

21790605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4220.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 21790605 is about 4668.0408095903. The cubic root of 21790605 is about 279.3121081699.

The spelling of 21790605 in words is "twenty-one million, seven hundred ninety thousand, six hundred five".