161557586 has 4 divisors (see below), whose sum is σ = 242336382. Its totient is φ = 80778792.

The previous prime is 161557573. The next prime is 161557603. The reversal of 161557586 is 685755161.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 110649361 + 50908225 = 10519^2 + 7135^2 .

It is a super-2 number, since 2×161557586² = 52201707188294792, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40389395 + ... + 40389398.

Almost surely, 2^161557586 is an apocalyptic number.

161557586 is a deficient number, since it is larger than the sum of its proper divisors (80778796).

161557586 is an equidigital number, since it uses as much as digits as its factorization.

161557586 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80778795.

The product of its digits is 252000, while the sum is 44.

The square root of 161557586 is about 12710.5305160721. The cubic root of 161557586 is about 544.6394787608.

The spelling of 161557586 in words is "one hundred sixty-one million, five hundred fifty-seven thousand, five hundred eighty-six".