64125781 has 2 divisors, whose sum is σ = 64125782. Its totient is φ = 64125780.

The previous prime is 64125769. The next prime is 64125797. The reversal of 64125781 is 18752146.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57623281 + 6502500 = 7591^2 + 2550^2 .

It is a cyclic number.

It is not a de Polignac number, because 64125781 - 2⁵ = 64125749 is a prime.

It is a super-2 number, since 2×64125781² = 8224231577719922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64125881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32062890 + 32062891.

It is an arithmetic number, because the mean of its divisors is an integer number (32062891).

Almost surely, 2^64125781 is an apocalyptic number.

It is an amenable number.

64125781 is a deficient number, since it is larger than the sum of its proper divisors (1).

64125781 is an equidigital number, since it uses as much as digits as its factorization.

64125781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13440, while the sum is 34.

The square root of 64125781 is about 8007.8574537763. The cubic root of 64125781 is about 400.2618722699.

The spelling of 64125781 in words is "sixty-four million, one hundred twenty-five thousand, seven hundred eighty-one".