166401521 has 16 divisors (see below), whose sum is σ = 201804288. Its totient is φ = 135129600.

The previous prime is 166401511. The next prime is 166401523. The reversal of 166401521 is 125104661.

It is a cyclic number.

It is not a de Polignac number, because 166401521 - 2¹⁸ = 166139377 is a prime.

It is a super-2 number, since 2×166401521² = 55378932382226882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166401523) 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, 14336 + ... + 23201.

It is an arithmetic number, because the mean of its divisors is an integer number (12612768).

Almost surely, 2^166401521 is an apocalyptic number.

166401521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166401521 is a deficient number, since it is larger than the sum of its proper divisors (35402767).

166401521 is a wasteful number, since it uses less digits than its factorization.

166401521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37592.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 166401521 is about 12899.6713524027. The cubic root of 166401521 is about 550.0292226897.

The spelling of 166401521 in words is "one hundred sixty-six million, four hundred one thousand, five hundred twenty-one".