66820555 has 8 divisors (see below), whose sum is σ = 80264592. Its totient is φ = 53403168.

The previous prime is 66820547. The next prime is 66820571. The reversal of 66820555 is 55502866.

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

It is a cyclic number.

It is not a de Polignac number, because 66820555 - 2³ = 66820547 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 649 + ... + 11578.

It is an arithmetic number, because the mean of its divisors is an integer number (10033074).

Almost surely, 2^66820555 is an apocalyptic number.

66820555 is a deficient number, since it is larger than the sum of its proper divisors (13444037).

66820555 is a wasteful number, since it uses less digits than its factorization.

66820555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13325.

The product of its (nonzero) digits is 72000, while the sum is 37.

The square root of 66820555 is about 8174.3840746566. The cubic root of 66820555 is about 405.7918865943.

The spelling of 66820555 in words is "sixty-six million, eight hundred twenty thousand, five hundred fifty-five".