21264981671 has 2 divisors, whose sum is σ = 21264981672. Its totient is φ = 21264981670.

The previous prime is 21264981653. The next prime is 21264981691. The reversal of 21264981671 is 17618946212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21264981671 - 2³⁴ = 4085112487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21264981631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632490835 + 10632490836.

It is an arithmetic number, because the mean of its divisors is an integer number (10632490836).

Almost surely, 2^21264981671 is an apocalyptic number.

21264981671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21264981671 is an equidigital number, since it uses as much as digits as its factorization.

21264981671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 47.

The spelling of 21264981671 in words is "twenty-one billion, two hundred sixty-four million, nine hundred eighty-one thousand, six hundred seventy-one".