166421503 has 4 divisors (see below), whose sum is σ = 167618920. Its totient is φ = 165224088.

The previous prime is 166421473. The next prime is 166421539. The reversal of 166421503 is 305124661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 305124661 = 31 ⋅9842731.

It is a cyclic number.

It is not a de Polignac number, because 166421503 - 2⁵ = 166421471 is a prime.

It is a super-2 number, since 2×166421503² = 55392233321558018, 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 (166421573) 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, 598500 + ... + 598777.

It is an arithmetic number, because the mean of its divisors is an integer number (41904730).

Almost surely, 2^166421503 is an apocalyptic number.

166421503 is a deficient number, since it is larger than the sum of its proper divisors (1197417).

166421503 is a wasteful number, since it uses less digits than its factorization.

166421503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1197416.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 166421503 is about 12900.4458450086. The cubic root of 166421503 is about 550.0512382017.

It can be divided in two parts, 16642 and 1503, that added together give a triangular number (18145 = T₁₉₀).

The spelling of 166421503 in words is "one hundred sixty-six million, four hundred twenty-one thousand, five hundred three".