161627891 has 4 divisors (see below), whose sum is σ = 171135432. Its totient is φ = 152120352.

The previous prime is 161627881. The next prime is 161627911. The reversal of 161627891 is 198726161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 198726161 = 1669 ⋅119069.

It is not a de Polignac number, because 161627891 - 2¹⁰ = 161626867 is a prime.

It is a super-2 number, since 2×161627891² = 52247150298215762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161627821) 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, 4753745 + ... + 4753778.

It is an arithmetic number, because the mean of its divisors is an integer number (42783858).

Almost surely, 2^161627891 is an apocalyptic number.

161627891 is a deficient number, since it is larger than the sum of its proper divisors (9507541).

161627891 is an equidigital number, since it uses as much as digits as its factorization.

161627891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9507540.

The product of its digits is 36288, while the sum is 41.

The square root of 161627891 is about 12713.2958354630. The cubic root of 161627891 is about 544.7184708744.

The spelling of 161627891 in words is "one hundred sixty-one million, six hundred twenty-seven thousand, eight hundred ninety-one".