21551513223533 has 2 divisors, whose sum is σ = 21551513223534. Its totient is φ = 21551513223532.

The previous prime is 21551513223523. The next prime is 21551513223551. The reversal of 21551513223533 is 33532231515512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14519247230569 + 7032265992964 = 3810413^2 + 2651842^2 .

It is a cyclic number.

It is not a de Polignac number, because 21551513223533 - 2⁴ = 21551513223517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21551513223523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775756611766 + 10775756611767.

It is an arithmetic number, because the mean of its divisors is an integer number (10775756611767).

Almost surely, 2^{21551513223533} is an apocalyptic number.

It is an amenable number.

21551513223533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551513223533 is an equidigital number, since it uses as much as digits as its factorization.

21551513223533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 405000, while the sum is 41.

The spelling of 21551513223533 in words is "twenty-one trillion, five hundred fifty-one billion, five hundred thirteen million, two hundred twenty-three thousand, five hundred thirty-three".