64688381 has 2 divisors, whose sum is σ = 64688382. Its totient is φ = 64688380.

The previous prime is 64688363. The next prime is 64688399. The reversal of 64688381 is 18388646.

It is a balanced prime because it is at equal distance from previous prime (64688363) and next prime (64688399).

It can be written as a sum of positive squares in only one way, i.e., 43112356 + 21576025 = 6566^2 + 4645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64688381 is a prime.

It is a super-2 number, since 2×64688381² = 8369173272802322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64688341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32344190 + 32344191.

It is an arithmetic number, because the mean of its divisors is an integer number (32344191).

Almost surely, 2^64688381 is an apocalyptic number.

It is an amenable number.

64688381 is a deficient number, since it is larger than the sum of its proper divisors (1).

64688381 is an equidigital number, since it uses as much as digits as its factorization.

64688381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 221184, while the sum is 44.

The square root of 64688381 is about 8042.9087400020. The cubic root of 64688381 is about 401.4290157885.

The spelling of 64688381 in words is "sixty-four million, six hundred eighty-eight thousand, three hundred eighty-one".