21621555034423 has 4 divisors (see below), whose sum is σ = 21686876953288. Its totient is φ = 21556233115560.

The previous prime is 21621555034319. The next prime is 21621555034441. The reversal of 21621555034423 is 32443055512612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21621555034423 - 2¹³ = 21621555026231 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21621555034423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621555934423) 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, 32660958936 + ... + 32660959597.

It is an arithmetic number, because the mean of its divisors is an integer number (5421719238322).

Almost surely, 2^{21621555034423} is an apocalyptic number.

21621555034423 is a deficient number, since it is larger than the sum of its proper divisors (65321918865).

21621555034423 is an equidigital number, since it uses as much as digits as its factorization.

21621555034423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65321918864.

The product of its (nonzero) digits is 864000, while the sum is 43.

The spelling of 21621555034423 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred fifty-five million, thirty-four thousand, four hundred twenty-three".