161778664 has 32 divisors (see below), whose sum is σ = 322470720. Its totient is φ = 75824896.

The previous prime is 161778611. The next prime is 161778667. The reversal of 161778664 is 466877161.

It is a super-2 number, since 2×161778664² = 52344672251249792, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161778667) 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 7 ways as a sum of consecutive naturals, for example, 33507 + ... + 38029.

It is an arithmetic number, because the mean of its divisors is an integer number (10077210).

Almost surely, 2^161778664 is an apocalyptic number.

It is an amenable number.

161778664 is a deficient number, since it is larger than the sum of its proper divisors (160692056).

161778664 is a wasteful number, since it uses less digits than its factorization.

161778664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4809 (or 4805 counting only the distinct ones).

The product of its digits is 338688, while the sum is 46.

The square root of 161778664 is about 12719.2241901776. The cubic root of 161778664 is about 544.8877966697.

The spelling of 161778664 in words is "one hundred sixty-one million, seven hundred seventy-eight thousand, six hundred sixty-four".