21621421707775 has 12 divisors (see below), whose sum is σ = 26818474077000. Its totient is φ = 17292033392480.

The previous prime is 21621421707719. The next prime is 21621421707779. The reversal of 21621421707775 is 57770712412612.

It is not a de Polignac number, because 21621421707775 - 2¹³ = 21621421699583 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621421707779) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 127512925 + ... + 127682374.

It is an arithmetic number, because the mean of its divisors is an integer number (2234872839750).

Almost surely, 2^{21621421707775} is an apocalyptic number.

21621421707775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21621421707775 is a deficient number, since it is larger than the sum of its proper divisors (5197052369225).

21621421707775 is a wasteful number, since it uses less digits than its factorization.

21621421707775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255198698 (or 255198693 counting only the distinct ones).

The product of its (nonzero) digits is 2304960, while the sum is 52.

The spelling of 21621421707775 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred twenty-one million, seven hundred seven thousand, seven hundred seventy-five".