21771002531 has 2 divisors, whose sum is σ = 21771002532. Its totient is φ = 21771002530.

The previous prime is 21771002479. The next prime is 21771002551. The reversal of 21771002531 is 13520017712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21771002531 - 2³⁰ = 20697260707 is a prime.

It is a super-2 number, since 2×21771002531² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21771002494 and 21771002503.

It is not a weakly prime, because it can be changed into another prime (21771002551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885501265 + 10885501266.

It is an arithmetic number, because the mean of its divisors is an integer number (10885501266).

Almost surely, 2^21771002531 is an apocalyptic number.

21771002531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771002531 is an equidigital number, since it uses as much as digits as its factorization.

21771002531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2940, while the sum is 29.

The spelling of 21771002531 in words is "twenty-one billion, seven hundred seventy-one million, two thousand, five hundred thirty-one".