161801691 has 8 divisors (see below), whose sum is σ = 216012864. Its totient is φ = 107729160.

The previous prime is 161801681. The next prime is 161801713. The reversal of 161801691 is 196108161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161801691 - 2¹¹ = 161799643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161801681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31905 + ... + 36626.

It is an arithmetic number, because the mean of its divisors is an integer number (27001608).

Almost surely, 2^161801691 is an apocalyptic number.

161801691 is a deficient number, since it is larger than the sum of its proper divisors (54211173).

161801691 is an equidigital number, since it uses as much as digits as its factorization.

161801691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69321.

The product of its (nonzero) digits is 2592, while the sum is 33.

The square root of 161801691 is about 12720.1293625497. The cubic root of 161801691 is about 544.9136479073.

It can be divided in two parts, 16180 and 1691, that added together give a palindrome (17871).

The spelling of 161801691 in words is "one hundred sixty-one million, eight hundred one thousand, six hundred ninety-one".