66156661 has 8 divisors (see below), whose sum is σ = 67836384. Its totient is φ = 64483440.

The previous prime is 66156659. The next prime is 66156677. The reversal of 66156661 is 16665166.

66156661 = T₁₅₀ + T₁₅₁ + ... + T₇₃₆.

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 66156661 - 2¹ = 66156659 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66156661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66151661) 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, 23931 + ... + 26551.

It is an arithmetic number, because the mean of its divisors is an integer number (8479548).

Almost surely, 2^66156661 is an apocalyptic number.

It is an amenable number.

66156661 is a deficient number, since it is larger than the sum of its proper divisors (1679723).

66156661 is a wasteful number, since it uses less digits than its factorization.

66156661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3251.

The product of its digits is 38880, while the sum is 37.

The square root of 66156661 is about 8133.6745078716. The cubic root of 66156661 is about 404.4434992537.

The spelling of 66156661 in words is "sixty-six million, one hundred fifty-six thousand, six hundred sixty-one".