21531207361 has 2 divisors, whose sum is σ = 21531207362. Its totient is φ = 21531207360.

The previous prime is 21531207349. The next prime is 21531207367. The reversal of 21531207361 is 16370213512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16326450625 + 5204756736 = 127775^2 + 72144^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531207361 - 2⁵ = 21531207329 is a prime.

It is not a weakly prime, because it can be changed into another prime (21531207367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765603680 + 10765603681.

It is an arithmetic number, because the mean of its divisors is an integer number (10765603681).

Almost surely, 2^21531207361 is an apocalyptic number.

It is an amenable number.

21531207361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531207361 is an equidigital number, since it uses as much as digits as its factorization.

21531207361 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The spelling of 21531207361 in words is "twenty-one billion, five hundred thirty-one million, two hundred seven thousand, three hundred sixty-one".