161978531 has 16 divisors (see below), whose sum is σ = 191315040. Its totient is φ = 135198720.

The previous prime is 161978527. The next prime is 161978569. The reversal of 161978531 is 135879161.

161978531 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 161978531 - 2² = 161978527 is a prime.

It is a super-2 number, since 2×161978531² = 52474089009835922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161978501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24665 + ... + 30533.

It is an arithmetic number, because the mean of its divisors is an integer number (11957190).

Almost surely, 2^161978531 is an apocalyptic number.

161978531 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161978531 is a deficient number, since it is larger than the sum of its proper divisors (29336509).

161978531 is a wasteful number, since it uses less digits than its factorization.

161978531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6086.

The product of its digits is 45360, while the sum is 41.

The square root of 161978531 is about 12727.0786514424. The cubic root of 161978531 is about 545.1120954512.

The spelling of 161978531 in words is "one hundred sixty-one million, nine hundred seventy-eight thousand, five hundred thirty-one".