166001721 has 8 divisors (see below), whose sum is σ = 227317824. Its totient is φ = 107676720.

The previous prime is 166001711. The next prime is 166001749. The reversal of 166001721 is 127100661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 166001721 - 2⁶ = 166001657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 166001691 and 166001700.

It is not an unprimeable number, because it can be changed into a prime (166001711) 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, 747645 + ... + 747866.

It is an arithmetic number, because the mean of its divisors is an integer number (28414728).

Almost surely, 2^166001721 is an apocalyptic number.

It is an amenable number.

166001721 is a deficient number, since it is larger than the sum of its proper divisors (61316103).

166001721 is a wasteful number, since it uses less digits than its factorization.

166001721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1495551.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 166001721 is about 12884.1655143048. The cubic root of 166001721 is about 549.5883652766.

The spelling of 166001721 in words is "one hundred sixty-six million, one thousand, seven hundred twenty-one".