64442781 has 24 divisors (see below), whose sum is σ = 102385920. Its totient is φ = 38810016.

The previous prime is 64442773. The next prime is 64442797. The reversal of 64442781 is 18724446.

64442781 is a `hidden beast` number, since 644 + 4 + 2 + 7 + 8 + 1 = 666.

It is not a de Polignac number, because 64442781 - 2³ = 64442773 is a prime.

It is a super-2 number, since 2×64442781² = 8305744046027922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64442761) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 361 + ... + 11358.

It is an arithmetic number, because the mean of its divisors is an integer number (4266080).

Almost surely, 2^64442781 is an apocalyptic number.

It is an amenable number.

64442781 is a deficient number, since it is larger than the sum of its proper divisors (37943139).

64442781 is a wasteful number, since it uses less digits than its factorization.

64442781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11785 (or 11782 counting only the distinct ones).

The product of its digits is 43008, while the sum is 36.

The square root of 64442781 is about 8027.6261123697. The cubic root of 64442781 is about 400.9203412227.

The spelling of 64442781 in words is "sixty-four million, four hundred forty-two thousand, seven hundred eighty-one".