21080377813 has 4 divisors (see below), whose sum is σ = 22996775808. Its totient is φ = 19163979820.

The previous prime is 21080377807. The next prime is 21080377823. The reversal of 21080377813 is 31877308012.

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-21080377813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21080377823) 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, 958198981 + ... + 958199002.

It is an arithmetic number, because the mean of its divisors is an integer number (5749193952).

Almost surely, 2^21080377813 is an apocalyptic number.

It is an amenable number.

21080377813 is a deficient number, since it is larger than the sum of its proper divisors (1916397995).

21080377813 is a wasteful number, since it uses less digits than its factorization.

21080377813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1916397994.

The product of its (nonzero) digits is 56448, while the sum is 40.

It can be divided in two parts, 21080 and 377813, that added together give a palindrome (398893).

The spelling of 21080377813 in words is "twenty-one billion, eighty million, three hundred seventy-seven thousand, eight hundred thirteen".