161634421 has 4 divisors (see below), whose sum is σ = 174067852. Its totient is φ = 149200992.

The previous prime is 161634401. The next prime is 161634443. The reversal of 161634421 is 124436161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124436161 = 521 ⋅238841.

It can be written as a sum of positive squares in 2 ways, for example, as 68724100 + 92910321 = 8290^2 + 9639^2 .

It is a cyclic number.

It is not a de Polignac number, because 161634421 - 2¹⁵ = 161601653 is a prime.

It is a super-2 number, since 2×161634421² = 52251372104010482, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161634421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161634401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6216696 + ... + 6216721.

It is an arithmetic number, because the mean of its divisors is an integer number (43516963).

Almost surely, 2^161634421 is an apocalyptic number.

It is an amenable number.

161634421 is a deficient number, since it is larger than the sum of its proper divisors (12433431).

161634421 is a wasteful number, since it uses less digits than its factorization.

161634421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12433430.

The product of its digits is 3456, while the sum is 28.

The square root of 161634421 is about 12713.5526506166. The cubic root of 161634421 is about 544.7258065797.

The spelling of 161634421 in words is "one hundred sixty-one million, six hundred thirty-four thousand, four hundred twenty-one".