21557364533 has 4 divisors (see below), whose sum is σ = 21573066828. Its totient is φ = 21541662240.

The previous prime is 21557364469. The next prime is 21557364593. The reversal of 21557364533 is 33546375512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21386722564 + 170641969 = 146242^2 + 13063^2 .

It is a cyclic number.

It is not a de Polignac number, because 21557364533 - 2⁶ = 21557364469 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 (21557364593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7849088 + ... + 7851833.

It is an arithmetic number, because the mean of its divisors is an integer number (5393266707).

Almost surely, 2^21557364533 is an apocalyptic number.

It is an amenable number.

21557364533 is a deficient number, since it is larger than the sum of its proper divisors (15702295).

21557364533 is a wasteful number, since it uses less digits than its factorization.

21557364533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15702294.

The product of its digits is 1134000, while the sum is 44.

The spelling of 21557364533 in words is "twenty-one billion, five hundred fifty-seven million, three hundred sixty-four thousand, five hundred thirty-three".