21255145533 has 24 divisors (see below), whose sum is σ = 31410377856. Its totient is φ = 13844160000.

The previous prime is 21255145507. The next prime is 21255145547. The reversal of 21255145533 is 33554155212.

21255145533 is a `hidden beast` number, since 2 + 12 + 551 + 45 + 53 + 3 = 666.

It is not a de Polignac number, because 21255145533 - 2⁸ = 21255145277 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255145333) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 197533 + ... + 285533.

It is an arithmetic number, because the mean of its divisors is an integer number (1308765744).

Almost surely, 2^21255145533 is an apocalyptic number.

It is an amenable number.

21255145533 is a deficient number, since it is larger than the sum of its proper divisors (10155232323).

21255145533 is a wasteful number, since it uses less digits than its factorization.

21255145533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88625 (or 88622 counting only the distinct ones).

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

The spelling of 21255145533 in words is "twenty-one billion, two hundred fifty-five million, one hundred forty-five thousand, five hundred thirty-three".