21305614621 has 4 divisors (see below), whose sum is σ = 21992892544. Its totient is φ = 20618336700.

The previous prime is 21305614613. The next prime is 21305614639. The reversal of 21305614621 is 12641650312.

It is a happy number.

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 not a de Polignac number, because 21305614621 - 2³ = 21305614613 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 687277891 = 21305614621 / (2 + 1 + 3 + 0 + 5 + 6 + 1 + 4 + 6 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305614661) 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, 343638915 + ... + 343638976.

It is an arithmetic number, because the mean of its divisors is an integer number (5498223136).

Almost surely, 2^21305614621 is an apocalyptic number.

It is an amenable number.

21305614621 is a deficient number, since it is larger than the sum of its proper divisors (687277923).

21305614621 is an equidigital number, since it uses as much as digits as its factorization.

21305614621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687277922.

The product of its (nonzero) digits is 8640, while the sum is 31.

The spelling of 21305614621 in words is "twenty-one billion, three hundred five million, six hundred fourteen thousand, six hundred twenty-one".