64191971 has 2 divisors, whose sum is σ = 64191972. Its totient is φ = 64191970.

The previous prime is 64191943. The next prime is 64191973. The reversal of 64191971 is 17919146.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 64191971 - 2¹⁰ = 64190947 is a prime.

It is a Sophie Germain prime.

Together with 64191973, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (64191973) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32095985 + 32095986.

It is an arithmetic number, because the mean of its divisors is an integer number (32095986).

Almost surely, 2^64191971 is an apocalyptic number.

64191971 is a deficient number, since it is larger than the sum of its proper divisors (1).

64191971 is an equidigital number, since it uses as much as digits as its factorization.

64191971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 38.

The square root of 64191971 is about 8011.9892036872. The cubic root of 64191971 is about 400.3995403692.

The spelling of 64191971 in words is "sixty-four million, one hundred ninety-one thousand, nine hundred seventy-one".