166840721890 has 16 divisors (see below), whose sum is σ = 313370399808. Its totient is φ = 63834710896.

The previous prime is 166840721843. The next prime is 166840721939. The reversal of 166840721890 is 98127048661.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 362696992 + ... + 362697451.

It is an arithmetic number, because the mean of its divisors is an integer number (19585649988).

Almost surely, 2^166840721890 is an apocalyptic number.

166840721890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

166840721890 is a deficient number, since it is larger than the sum of its proper divisors (146529677918).

166840721890 is a wasteful number, since it uses less digits than its factorization.

166840721890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725394473.

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 166840721890 in words is "one hundred sixty-six billion, eight hundred forty million, seven hundred twenty-one thousand, eight hundred ninety".