66978659 has 8 divisors (see below), whose sum is σ = 73135920. Its totient is φ = 60832800.

The previous prime is 66978581. The next prime is 66978673. The reversal of 66978659 is 95687966.

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-66978659 is a prime.

It is a super-2 number, since 2×66978659² = 8972281522876562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66978689) 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, 13589 + ... + 17849.

It is an arithmetic number, because the mean of its divisors is an integer number (9141990).

Almost surely, 2^66978659 is an apocalyptic number.

66978659 is a deficient number, since it is larger than the sum of its proper divisors (6157261).

66978659 is a wasteful number, since it uses less digits than its factorization.

66978659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5701.

The product of its digits is 4898880, while the sum is 56.

The square root of 66978659 is about 8184.0490589927. The cubic root of 66978659 is about 406.1116823319. Note that the first 3 decimals are identical.

The spelling of 66978659 in words is "sixty-six million, nine hundred seventy-eight thousand, six hundred fifty-nine".