21790813826 has 8 divisors (see below), whose sum is σ = 34608939660. Its totient is φ = 10254500608.

The previous prime is 21790813813. The next prime is 21790813831. The reversal of 21790813826 is 62831809712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16841550625 + 4949263201 = 129775^2 + 70351^2 .

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

It is a Curzon 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, 320453111 + ... + 320453178.

Almost surely, 2^21790813826 is an apocalyptic number.

21790813826 is a deficient number, since it is larger than the sum of its proper divisors (12818125834).

21790813826 is a wasteful number, since it uses less digits than its factorization.

21790813826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 640906308.

The product of its (nonzero) digits is 290304, while the sum is 47.

The spelling of 21790813826 in words is "twenty-one billion, seven hundred ninety million, eight hundred thirteen thousand, eight hundred twenty-six".