21451430621 has 4 divisors (see below), whose sum is σ = 21605757600. Its totient is φ = 21297103644.

The previous prime is 21451430573. The next prime is 21451430629. The reversal of 21451430621 is 12603415412.

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-21451430621 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 (21451430629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77163281 + ... + 77163558.

It is an arithmetic number, because the mean of its divisors is an integer number (5401439400).

Almost surely, 2^21451430621 is an apocalyptic number.

It is an amenable number.

21451430621 is a deficient number, since it is larger than the sum of its proper divisors (154326979).

21451430621 is a wasteful number, since it uses less digits than its factorization.

21451430621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154326978.

The product of its (nonzero) digits is 5760, while the sum is 29.

The spelling of 21451430621 in words is "twenty-one billion, four hundred fifty-one million, four hundred thirty thousand, six hundred twenty-one".