21551533425 has 36 divisors (see below), whose sum is σ = 39932278620. Its totient is φ = 11097797760.

The previous prime is 21551533411. The next prime is 21551533457. The reversal of 21551533425 is 52433515512.

21551533425 is a `hidden beast` number, since 2 + 1 + 551 + 53 + 34 + 25 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 866478096 + 20685055329 = 29436^2 + 143823^2 .

It is not a de Polignac number, because 21551533425 - 2⁹ = 21551532913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21551533425.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1644934 + ... + 1657983.

Almost surely, 2^21551533425 is an apocalyptic number.

21551533425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21551533425 is a deficient number, since it is larger than the sum of its proper divisors (18380745195).

21551533425 is a wasteful number, since it uses less digits than its factorization.

21551533425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3302962 (or 3302954 counting only the distinct ones).

The product of its digits is 90000, while the sum is 36.

The spelling of 21551533425 in words is "twenty-one billion, five hundred fifty-one million, five hundred thirty-three thousand, four hundred twenty-five".