66400681 has 8 divisors (see below), whose sum is σ = 68325824. Its totient is φ = 64482480.

The previous prime is 66400661. The next prime is 66400751. The reversal of 66400681 is 18600466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66400681 is a prime.

It is a super-2 number, since 2×66400681² = 8818100874527522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66400601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22396 + ... + 25186.

It is an arithmetic number, because the mean of its divisors is an integer number (8540728).

Almost surely, 2^66400681 is an apocalyptic number.

It is an amenable number.

66400681 is a deficient number, since it is larger than the sum of its proper divisors (1925143).

66400681 is a wasteful number, since it uses less digits than its factorization.

66400681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3471.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 66400681 is about 8148.6613010973. The cubic root of 66400681 is about 404.9401547503.

It can be divided in two parts, 66400 and 681, that added together give a square (67081 = 259²).

The spelling of 66400681 in words is "sixty-six million, four hundred thousand, six hundred eighty-one".