161421538 has 4 divisors (see below), whose sum is σ = 242132310. Its totient is φ = 80710768.

The previous prime is 161421523. The next prime is 161421539. The reversal of 161421538 is 835124161.

161421538 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 835124161 = 73 ⋅11440057.

It can be written as a sum of positive squares in only one way, i.e., 107060409 + 54361129 = 10347^2 + 7373^2 .

It is not an unprimeable number, because it can be changed into a prime (161421539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40355383 + ... + 40355386.

Almost surely, 2^161421538 is an apocalyptic number.

161421538 is a deficient number, since it is larger than the sum of its proper divisors (80710772).

161421538 is an equidigital number, since it uses as much as digits as its factorization.

161421538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80710771.

The product of its digits is 5760, while the sum is 31.

The square root of 161421538 is about 12705.1776059998. The cubic root of 161421538 is about 544.4865551244.

Adding to 161421538 its reverse (835124161), we get a palindrome (996545699).

The spelling of 161421538 in words is "one hundred sixty-one million, four hundred twenty-one thousand, five hundred thirty-eight".