66790057 has 4 divisors (see below), whose sum is σ = 66806740. Its totient is φ = 66773376.

The previous prime is 66790039. The next prime is 66790079. The reversal of 66790057 is 75009766.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 37748736 + 29041321 = 6144^2 + 5389^2 .

It is a 3-Lehmer number, since φ(66790057) divides (66790057-1)³.

It is a cyclic number.

It is not a de Polignac number, because 66790057 - 2¹⁹ = 66265769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66790007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1669 + ... + 11677.

It is an arithmetic number, because the mean of its divisors is an integer number (16701685).

It is a Poulet number, since it divides 2^66790056-1.

Almost surely, 2^66790057 is an apocalyptic number.

66790057 is the 6673-rd pentagonal number.

It is an amenable number.

66790057 is a deficient number, since it is larger than the sum of its proper divisors (16683).

66790057 is a wasteful number, since it uses less digits than its factorization.

66790057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16682.

The product of its (nonzero) digits is 79380, while the sum is 40.

The square root of 66790057 is about 8172.5184001016. The cubic root of 66790057 is about 405.7301405030.

The spelling of 66790057 in words is "sixty-six million, seven hundred ninety thousand, fifty-seven".