64739881 has 2 divisors, whose sum is σ = 64739882. Its totient is φ = 64739880.

The previous prime is 64739879. The next prime is 64739921. The reversal of 64739881 is 18893746.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43033600 + 21706281 = 6560^2 + 4659^2 .

It is a cyclic number.

It is not a de Polignac number, because 64739881 - 2¹ = 64739879 is a prime.

It is a super-2 number, since 2×64739881² = 8382504383788322, which contains 22 as substring.

Together with 64739879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (64739581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32369940 + 32369941.

It is an arithmetic number, because the mean of its divisors is an integer number (32369941).

Almost surely, 2^64739881 is an apocalyptic number.

It is an amenable number.

64739881 is a deficient number, since it is larger than the sum of its proper divisors (1).

64739881 is an equidigital number, since it uses as much as digits as its factorization.

64739881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 46.

The square root of 64739881 is about 8046.1096810819. The cubic root of 64739881 is about 401.5355166787.

The spelling of 64739881 in words is "sixty-four million, seven hundred thirty-nine thousand, eight hundred eighty-one".