21300531521 has 2 divisors, whose sum is σ = 21300531522. Its totient is φ = 21300531520.

The previous prime is 21300531509. The next prime is 21300531583. The reversal of 21300531521 is 12513500312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20010931600 + 1289599921 = 141460^2 + 35911^2 .

It is a cyclic number.

It is not a de Polignac number, because 21300531521 - 2²² = 21296337217 is a prime.

It is a super-2 number, since 2×21300531521² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21300531121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10650265760 + 10650265761.

It is an arithmetic number, because the mean of its divisors is an integer number (10650265761).

Almost surely, 2^21300531521 is an apocalyptic number.

It is an amenable number.

21300531521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21300531521 is an equidigital number, since it uses as much as digits as its factorization.

21300531521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 23.

The spelling of 21300531521 in words is "twenty-one billion, three hundred million, five hundred thirty-one thousand, five hundred twenty-one".