161505651 has 4 divisors (see below), whose sum is σ = 215340872. Its totient is φ = 107670432.

The previous prime is 161505649. The next prime is 161505667. The reversal of 161505651 is 156505161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 156505161 = 3 ⋅52168387.

It is not a de Polignac number, because 161505651 - 2¹ = 161505649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161505671) 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, 26917606 + ... + 26917611.

It is an arithmetic number, because the mean of its divisors is an integer number (53835218).

Almost surely, 2^161505651 is an apocalyptic number.

161505651 is a deficient number, since it is larger than the sum of its proper divisors (53835221).

161505651 is an equidigital number, since it uses as much as digits as its factorization.

161505651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53835220.

The product of its (nonzero) digits is 4500, while the sum is 30.

The square root of 161505651 is about 12708.4873608152. The cubic root of 161505651 is about 544.5811117857.

The spelling of 161505651 in words is "one hundred sixty-one million, five hundred five thousand, six hundred fifty-one".