66215557 has 8 divisors (see below), whose sum is σ = 66763872. Its totient is φ = 65670000.

The previous prime is 66215549. The next prime is 66215563. The reversal of 66215557 is 75551266.

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 66215557 - 2³ = 66215549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66215587) 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, 82683 + ... + 83479.

It is an arithmetic number, because the mean of its divisors is an integer number (8345484).

Almost surely, 2^66215557 is an apocalyptic number.

It is an amenable number.

66215557 is a deficient number, since it is larger than the sum of its proper divisors (548315).

66215557 is a wasteful number, since it uses less digits than its factorization.

66215557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1379.

The product of its digits is 63000, while the sum is 37.

The square root of 66215557 is about 8137.2942063072. The cubic root of 66215557 is about 404.5634823304.

The spelling of 66215557 in words is "sixty-six million, two hundred fifteen thousand, five hundred fifty-seven".