161638445 has 4 divisors (see below), whose sum is σ = 193966140. Its totient is φ = 129310752.

The previous prime is 161638429. The next prime is 161638487. The reversal of 161638445 is 544836161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 127193284 + 34445161 = 11278^2 + 5869^2 .

It is a cyclic number.

It is not a de Polignac number, because 161638445 - 2⁴ = 161638429 is a prime.

It is a super-2 number, since 2×161638445² = 52253973804036050, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 161638399 and 161638408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16163840 + ... + 16163849.

It is an arithmetic number, because the mean of its divisors is an integer number (48491535).

Almost surely, 2^161638445 is an apocalyptic number.

It is an amenable number.

161638445 is a deficient number, since it is larger than the sum of its proper divisors (32327695).

161638445 is an equidigital number, since it uses as much as digits as its factorization.

161638445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32327694.

The product of its digits is 69120, while the sum is 38.

The square root of 161638445 is about 12713.7109059472. The cubic root of 161638445 is about 544.7303269833.

The spelling of 161638445 in words is "one hundred sixty-one million, six hundred thirty-eight thousand, four hundred forty-five".