161685834251 has 4 divisors (see below), whose sum is σ = 165125958432. Its totient is φ = 158245710072.

The previous prime is 161685834131. The next prime is 161685834257. The reversal of 161685834251 is 152438586161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 152438586161 = 22291 ⋅6838571.

It is a cyclic number.

It is not a de Polignac number, because 161685834251 - 2²² = 161681639947 is a prime.

It is a super-2 number, since 2×161685834251² (a number of 23 digits) 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 161685834251.

It is not an unprimeable number, because it can be changed into a prime (161685834257) 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, 1720062020 + ... + 1720062113.

It is an arithmetic number, because the mean of its divisors is an integer number (41281489608).

Almost surely, 2^161685834251 is an apocalyptic number.

161685834251 is a deficient number, since it is larger than the sum of its proper divisors (3440124181).

161685834251 is an equidigital number, since it uses as much as digits as its factorization.

161685834251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3440124180.

The product of its digits is 1382400, while the sum is 50.

The spelling of 161685834251 in words is "one hundred sixty-one billion, six hundred eighty-five million, eight hundred thirty-four thousand, two hundred fifty-one".