21621200105621 has 4 divisors (see below), whose sum is σ = 21791445775872. Its totient is φ = 21450954435372.

The previous prime is 21621200105573. The next prime is 21621200105629. The reversal of 21621200105621 is 12650100212612.

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-21621200105621 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 (21621200105629) 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, 85122834935 + ... + 85122835188.

It is an arithmetic number, because the mean of its divisors is an integer number (5447861443968).

Almost surely, 2^{21621200105621} is an apocalyptic number.

It is an amenable number.

21621200105621 is a deficient number, since it is larger than the sum of its proper divisors (170245670251).

21621200105621 is a wasteful number, since it uses less digits than its factorization.

21621200105621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170245670250.

The product of its (nonzero) digits is 2880, while the sum is 29.

The spelling of 21621200105621 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred million, one hundred five thousand, six hundred twenty-one".