161688477 has 4 divisors (see below), whose sum is σ = 215584640. Its totient is φ = 107792316.

The previous prime is 161688451. The next prime is 161688481. The reversal of 161688477 is 774886161.

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.

It is not a de Polignac number, because 161688477 - 2⁷ = 161688349 is a prime.

It is a super-2 number, since 2×161688477² = 52286327189159058, 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 (161688437) 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, 26948077 + ... + 26948082.

It is an arithmetic number, because the mean of its divisors is an integer number (53896160).

Almost surely, 2^161688477 is an apocalyptic number.

It is an amenable number.

161688477 is a deficient number, since it is larger than the sum of its proper divisors (53896163).

161688477 is an equidigital number, since it uses as much as digits as its factorization.

161688477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53896162.

The product of its digits is 451584, while the sum is 48.

The square root of 161688477 is about 12715.6783932278. The cubic root of 161688477 is about 544.7865247033.

It can be divided in two parts, 161688 and 477, that added together give a triangular number (162165 = T₅₆₉).

The spelling of 161688477 in words is "one hundred sixty-one million, six hundred eighty-eight thousand, four hundred seventy-seven".