21790379521 has 4 divisors (see below), whose sum is σ = 21983214852. Its totient is φ = 21597544192.

The previous prime is 21790379509. The next prime is 21790379543. The reversal of 21790379521 is 12597309712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9142228225 + 12648151296 = 95615^2 + 112464^2 .

It is a cyclic number.

It is not a de Polignac number, because 21790379521 - 2⁵ = 21790379489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21790379581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96417496 + ... + 96417721.

It is an arithmetic number, because the mean of its divisors is an integer number (5495803713).

Almost surely, 2^21790379521 is an apocalyptic number.

It is an amenable number.

21790379521 is a deficient number, since it is larger than the sum of its proper divisors (192835331).

21790379521 is a wasteful number, since it uses less digits than its factorization.

21790379521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192835330.

The product of its (nonzero) digits is 238140, while the sum is 46.

The spelling of 21790379521 in words is "twenty-one billion, seven hundred ninety million, three hundred seventy-nine thousand, five hundred twenty-one".