64881391 has 2 divisors, whose sum is σ = 64881392. Its totient is φ = 64881390.

The previous prime is 64881361. The next prime is 64881403. The reversal of 64881391 is 19318846.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64881391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64881331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32440695 + 32440696.

It is an arithmetic number, because the mean of its divisors is an integer number (32440696).

Almost surely, 2^64881391 is an apocalyptic number.

64881391 is a deficient number, since it is larger than the sum of its proper divisors (1).

64881391 is an equidigital number, since it uses as much as digits as its factorization.

64881391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 40.

The square root of 64881391 is about 8054.8985716767. The cubic root of 64881391 is about 401.8278657935.

The spelling of 64881391 in words is "sixty-four million, eight hundred eighty-one thousand, three hundred ninety-one".