66161556 has 48 divisors (see below), whose sum is σ = 172708480. Its totient is φ = 21902400.

The previous prime is 66161551. The next prime is 66161561. The reversal of 66161556 is 65516166.

It is an interprime number because it is at equal distance from previous prime (66161551) and next prime (66161561).

It is a super-2 number, since 2×66161556² = 8754702984682272, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 66161556.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66161551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14280 + ... + 18336.

Almost surely, 2^66161556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66161556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86354240).

66161556 is an abundant number, since it is smaller than the sum of its proper divisors (106546924).

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

66161556 is a wasteful number, since it uses less digits than its factorization.

66161556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4221 (or 4213 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 66161556 is about 8133.9754118143. The cubic root of 66161556 is about 404.4534740724.

The spelling of 66161556 in words is "sixty-six million, one hundred sixty-one thousand, five hundred fifty-six".