21215866432571 has 2 divisors, whose sum is σ = 21215866432572. Its totient is φ = 21215866432570.

The previous prime is 21215866432543. The next prime is 21215866432583. The reversal of 21215866432571 is 17523466851212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21215866432571 - 2⁶ = 21215866432507 is a prime.

It is a super-2 number, since 2×21215866432571² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21215866432171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607933216285 + 10607933216286.

It is an arithmetic number, because the mean of its divisors is an integer number (10607933216286).

Almost surely, 2^{21215866432571} is an apocalyptic number.

21215866432571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215866432571 is an equidigital number, since it uses as much as digits as its factorization.

21215866432571 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4838400, while the sum is 53.

The spelling of 21215866432571 in words is "twenty-one trillion, two hundred fifteen billion, eight hundred sixty-six million, four hundred thirty-two thousand, five hundred seventy-one".