161651554 has 4 divisors (see below), whose sum is σ = 242477334. Its totient is φ = 80825776.

The previous prime is 161651543. The next prime is 161651573. The reversal of 161651554 is 455156161.

161651554 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 455156161 = 43 ⋅10585027.

It can be written as a sum of positive squares in only one way, i.e., 128300929 + 33350625 = 11327^2 + 5775^2 .

It is a super-2 number, since 2×161651554² = 52262449821229832, which contains 22 as substring.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 40412887 + ... + 40412890.

Almost surely, 2^161651554 is an apocalyptic number.

161651554 is a deficient number, since it is larger than the sum of its proper divisors (80825780).

161651554 is an equidigital number, since it uses as much as digits as its factorization.

161651554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80825779.

The product of its digits is 18000, while the sum is 34.

The square root of 161651554 is about 12714.2264412744. The cubic root of 161651554 is about 544.7450525989.

The spelling of 161651554 in words is "one hundred sixty-one million, six hundred fifty-one thousand, five hundred fifty-four".