161978801 has 4 divisors (see below), whose sum is σ = 162692592. Its totient is φ = 161265012.

The previous prime is 161978783. The next prime is 161978809. The reversal of 161978801 is 108879161.

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: 108879161 = 31 ⋅3512231.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161978801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161978809) 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, 356555 + ... + 357008.

It is an arithmetic number, because the mean of its divisors is an integer number (40673148).

Almost surely, 2^161978801 is an apocalyptic number.

It is an amenable number.

161978801 is a deficient number, since it is larger than the sum of its proper divisors (713791).

161978801 is an equidigital number, since it uses as much as digits as its factorization.

161978801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713790.

The product of its (nonzero) digits is 24192, while the sum is 41.

The square root of 161978801 is about 12727.0892587426. The cubic root of 161978801 is about 545.1123983312.

The spelling of 161978801 in words is "one hundred sixty-one million, nine hundred seventy-eight thousand, eight hundred one".