21790345 has 16 divisors (see below), whose sum is σ = 27818640. Its totient is φ = 16328704.

The previous prime is 21790309. The next prime is 21790369. The reversal of 21790345 is 54309712.

It can be written as a sum of positive squares in 8 ways, for example, as 1115136 + 20675209 = 1056^2 + 4547^2 .

It is not a de Polignac number, because 21790345 - 2¹¹ = 21788297 is a prime.

It is a plaindrome in base 11.

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 15 ways as a sum of consecutive naturals, for example, 22389 + ... + 23341.

It is an arithmetic number, because the mean of its divisors is an integer number (1738665).

Almost surely, 2^21790345 is an apocalyptic number.

It is an amenable number.

21790345 is a deficient number, since it is larger than the sum of its proper divisors (6028295).

21790345 is a wasteful number, since it uses less digits than its factorization.

21790345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1244.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21790345 is about 4668.0129605647. The cubic root of 21790345 is about 279.3109972716.

The spelling of 21790345 in words is "twenty-one million, seven hundred ninety thousand, three hundred forty-five".