166981815 has 144 divisors (see below), whose sum is σ = 392718144. Its totient is φ = 63866880.

The previous prime is 166981811. The next prime is 166981819. The reversal of 166981815 is 518189661.

It is an interprime number because it is at equal distance from previous prime (166981811) and next prime (166981819).

It is not a de Polignac number, because 166981815 - 2² = 166981811 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166981811) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 495327 + ... + 495663.

Almost surely, 2^166981815 is an apocalyptic number.

166981815 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

166981815 is an abundant number, since it is smaller than the sum of its proper divisors (225736329).

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

166981815 is a wasteful number, since it uses less digits than its factorization.

166981815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390 (or 376 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 166981815 is about 12922.1443653908. The cubic root of 166981815 is about 550.6678553733.

The spelling of 166981815 in words is "one hundred sixty-six million, nine hundred eighty-one thousand, eight hundred fifteen".