66999790 has 32 divisors (see below), whose sum is σ = 141686496. Its totient is φ = 22488960.

The previous prime is 66999767. The next prime is 66999797. The reversal of 66999790 is 9799966.

It is a Harshad number since it is a multiple of its sum of digits (55).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66999797) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21997 + ... + 24856.

It is an arithmetic number, because the mean of its divisors is an integer number (4427703).

Almost surely, 2^66999790 is an apocalyptic number.

66999790 is an abundant number, since it is smaller than the sum of its proper divisors (74686706).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66999790 is a wasteful number, since it uses less digits than its factorization.

66999790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46884.

The product of its (nonzero) digits is 1653372, while the sum is 55.

The square root of 66999790 is about 8185.3399440707. The cubic root of 66999790 is about 406.1543857033.

The spelling of 66999790 in words is "sixty-six million, nine hundred ninety-nine thousand, seven hundred ninety".