21531333999971 has 2 divisors, whose sum is σ = 21531333999972. Its totient is φ = 21531333999970.

The previous prime is 21531333999941. The next prime is 21531334000069. The reversal of 21531333999971 is 17999933313512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21531333999971 - 2²⁶ = 21531266891107 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21531333999898 and 21531333999907.

It is not a weakly prime, because it can be changed into another prime (21531333999941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765666999985 + 10765666999986.

It is an arithmetic number, because the mean of its divisors is an integer number (10765666999986).

Almost surely, 2^{21531333999971} is an apocalyptic number.

21531333999971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531333999971 is an equidigital number, since it uses as much as digits as its factorization.

21531333999971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37200870, while the sum is 65.

The spelling of 21531333999971 in words is "twenty-one trillion, five hundred thirty-one billion, three hundred thirty-three million, nine hundred ninety-nine thousand, nine hundred seventy-one".