66409994 has 24 divisors (see below), whose sum is σ = 116960580. Its totient is φ = 28195776.

The previous prime is 66409991. The next prime is 66410023. The reversal of 66409994 is 49990466.

It can be written as a sum of positive squares in 2 ways, for example, as 63123025 + 3286969 = 7945^2 + 1813^2 .

It is not an unprimeable number, because it can be changed into a prime (66409991) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7574 + ... + 13790.

Almost surely, 2^66409994 is an apocalyptic number.

66409994 is a deficient number, since it is larger than the sum of its proper divisors (50550586).

66409994 is a wasteful number, since it uses less digits than its factorization.

66409994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6342 (or 6335 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 47.

The square root of 66409994 is about 8149.2327246189. The cubic root of 66409994 is about 404.9590854365.

The spelling of 66409994 in words is "sixty-six million, four hundred nine thousand, nine hundred ninety-four".