161640541 has 4 divisors (see below), whose sum is σ = 166854784. Its totient is φ = 156426300.

The previous prime is 161640529. The next prime is 161640587. The reversal of 161640541 is 145046161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 145046161 = 13 ⋅11157397.

It is a cyclic number.

It is not a de Polignac number, because 161640541 - 2¹¹ = 161638493 is a prime.

It is a super-2 number, since 2×161640541² = 52255328989545362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161640041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2607075 + ... + 2607136.

It is an arithmetic number, because the mean of its divisors is an integer number (41713696).

Almost surely, 2^161640541 is an apocalyptic number.

It is an amenable number.

161640541 is a deficient number, since it is larger than the sum of its proper divisors (5214243).

161640541 is an equidigital number, since it uses as much as digits as its factorization.

161640541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5214242.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 161640541 is about 12713.7933363729. The cubic root of 161640541 is about 544.7326815177.

The spelling of 161640541 in words is "one hundred sixty-one million, six hundred forty thousand, five hundred forty-one".