163978561 has 8 divisors (see below), whose sum is σ = 173844224. Its totient is φ = 154398960.

The previous prime is 163978543. The next prime is 163978567. The reversal of 163978561 is 165879361.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 163978561 - 2⁷ = 163978433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (163978567) 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, 70335 + ... + 72628.

It is an arithmetic number, because the mean of its divisors is an integer number (21730528).

Almost surely, 2^163978561 is an apocalyptic number.

It is an amenable number.

163978561 is a deficient number, since it is larger than the sum of its proper divisors (9865663).

163978561 is a wasteful number, since it uses less digits than its factorization.

163978561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143031.

The product of its digits is 272160, while the sum is 46.

The square root of 163978561 is about 12805.4113951876. The cubic root of 163978561 is about 547.3465146654.

It can be divided in two parts, 1639 and 78561, that added together give a triangular number (80200 = T₄₀₀).

The spelling of 163978561 in words is "one hundred sixty-three million, nine hundred seventy-eight thousand, five hundred sixty-one".