21973072813 has 4 divisors (see below), whose sum is σ = 21973770268. Its totient is φ = 21972375360.

The previous prime is 21973072783. The next prime is 21973072871. The reversal of 21973072813 is 31827037912.

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 16568323524 + 5404749289 = 128718^2 + 73517^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21973072813 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21973072813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973073813) 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, 299118 + ... + 365263.

It is an arithmetic number, because the mean of its divisors is an integer number (5493442567).

Almost surely, 2^21973072813 is an apocalyptic number.

It is an amenable number.

21973072813 is a deficient number, since it is larger than the sum of its proper divisors (697455).

21973072813 is an equidigital number, since it uses as much as digits as its factorization.

21973072813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 697454.

The product of its (nonzero) digits is 127008, while the sum is 43.

The spelling of 21973072813 in words is "twenty-one billion, nine hundred seventy-three million, seventy-two thousand, eight hundred thirteen".