20856516413 has 4 divisors (see below), whose sum is σ = 20858243328. Its totient is φ = 20854789500.

The previous prime is 20856516407. The next prime is 20856516427. The reversal of 20856516413 is 31461565802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20856516413 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20856516493) 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, 845213 + ... + 869538.

It is an arithmetic number, because the mean of its divisors is an integer number (5214560832).

Almost surely, 2^20856516413 is an apocalyptic number.

It is an amenable number.

20856516413 is a deficient number, since it is larger than the sum of its proper divisors (1726915).

20856516413 is a wasteful number, since it uses less digits than its factorization.

20856516413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1726914.

The product of its (nonzero) digits is 172800, while the sum is 41.

The spelling of 20856516413 in words is "twenty billion, eight hundred fifty-six million, five hundred sixteen thousand, four hundred thirteen".