166446421 has 4 divisors (see below), whose sum is σ = 170317312. Its totient is φ = 162575532.

The previous prime is 166446419. The next prime is 166446433. The reversal of 166446421 is 124644661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 124644661 = 109 ⋅1143529.

It is a cyclic number.

It is not a de Polignac number, because 166446421 - 2¹ = 166446419 is a prime.

It is a super-2 number, since 2×166446421² = 55408822127418482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166446451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1935381 + ... + 1935466.

It is an arithmetic number, because the mean of its divisors is an integer number (42579328).

Almost surely, 2^166446421 is an apocalyptic number.

It is an amenable number.

166446421 is a deficient number, since it is larger than the sum of its proper divisors (3870891).

166446421 is an equidigital number, since it uses as much as digits as its factorization.

166446421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3870890.

The product of its digits is 27648, while the sum is 34.

The square root of 166446421 is about 12901.4115894347. The cubic root of 166446421 is about 550.0786895676.

The spelling of 166446421 in words is "one hundred sixty-six million, four hundred forty-six thousand, four hundred twenty-one".