21551413775 has 6 divisors (see below), whose sum is σ = 26723753112. Its totient is φ = 17241131000.

The previous prime is 21551413729. The next prime is 21551413777. The reversal of 21551413775 is 57731415512.

It is not a de Polignac number, because 21551413775 - 2¹⁸ = 21551151631 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 (21551413777) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 431028251 + ... + 431028300.

It is an arithmetic number, because the mean of its divisors is an integer number (4453958852).

Almost surely, 2^21551413775 is an apocalyptic number.

21551413775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21551413775 is a deficient number, since it is larger than the sum of its proper divisors (5172339337).

21551413775 is an equidigital number, since it uses as much as digits as its factorization.

21551413775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862056561 (or 862056556 counting only the distinct ones).

The product of its digits is 147000, while the sum is 41.

The spelling of 21551413775 in words is "twenty-one billion, five hundred fifty-one million, four hundred thirteen thousand, seven hundred seventy-five".