21531231529 has 2 divisors, whose sum is σ = 21531231530. Its totient is φ = 21531231528.

The previous prime is 21531231517. The next prime is 21531231539. The reversal of 21531231529 is 92513213512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20058207129 + 1473024400 = 141627^2 + 38380^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531231529 - 2⁵ = 21531231497 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21531231494 and 21531231503.

It is not a weakly prime, because it can be changed into another prime (21531231539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765615764 + 10765615765.

It is an arithmetic number, because the mean of its divisors is an integer number (10765615765).

Almost surely, 2^21531231529 is an apocalyptic number.

It is an amenable number.

21531231529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531231529 is an equidigital number, since it uses as much as digits as its factorization.

21531231529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 34.

The spelling of 21531231529 in words is "twenty-one billion, five hundred thirty-one million, two hundred thirty-one thousand, five hundred twenty-nine".