66186981 has 24 divisors (see below), whose sum is σ = 110807424. Its totient is φ = 37285920.

The previous prime is 66186979. The next prime is 66187003. The reversal of 66186981 is 18968166.

It is a happy number.

It is not a de Polignac number, because 66186981 - 2¹ = 66186979 is a prime.

It is a super-2 number, since 2×66186981² = 8761432907788722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66186931) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2926 + ... + 11871.

It is an arithmetic number, because the mean of its divisors is an integer number (4616976).

Almost surely, 2^66186981 is an apocalyptic number.

It is an amenable number.

66186981 is a deficient number, since it is larger than the sum of its proper divisors (44620443).

66186981 is a wasteful number, since it uses less digits than its factorization.

66186981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14881 (or 14878 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 66186981 is about 8135.5381506081. The cubic root of 66186981 is about 404.5052761220.

The spelling of 66186981 in words is "sixty-six million, one hundred eighty-six thousand, nine hundred eighty-one".