21425633881 has 2 divisors, whose sum is σ = 21425633882. Its totient is φ = 21425633880.

The previous prime is 21425633863. The next prime is 21425633909. The reversal of 21425633881 is 18833652412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12536161225 + 8889472656 = 111965^2 + 94284^2 .

It is a cyclic number.

It is not a de Polignac number, because 21425633881 - 2¹⁷ = 21425502809 is a prime.

It is a super-2 number, since 2×21425633881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21425637881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712816940 + 10712816941.

It is an arithmetic number, because the mean of its divisors is an integer number (10712816941).

Almost surely, 2^21425633881 is an apocalyptic number.

It is an amenable number.

21425633881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21425633881 is an equidigital number, since it uses as much as digits as its factorization.

21425633881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 276480, while the sum is 43.

The spelling of 21425633881 in words is "twenty-one billion, four hundred twenty-five million, six hundred thirty-three thousand, eight hundred eighty-one".