1661605155 has 48 divisors (see below), whose sum is σ = 3371868864. Its totient is φ = 741058560.

The previous prime is 1661605151. The next prime is 1661605171. The reversal of 1661605155 is 5515061661.

It is not a de Polignac number, because 1661605155 - 2² = 1661605151 is a prime.

It is a super-2 number, since 2×1661605155² = 5521863382245148050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1661605151) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 51414 + ... + 77243.

It is an arithmetic number, because the mean of its divisors is an integer number (70247268).

Almost surely, 2^1661605155 is an apocalyptic number.

1661605155 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1661605155 is an abundant number, since it is smaller than the sum of its proper divisors (1710263709).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661605155 is a wasteful number, since it uses less digits than its factorization.

1661605155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128716 (or 128713 counting only the distinct ones).

The product of its (nonzero) digits is 27000, while the sum is 36.

The square root of 1661605155 is about 40762.7913053069. The cubic root of 1661605155 is about 1184.4296673295.

The spelling of 1661605155 in words is "one billion, six hundred sixty-one million, six hundred five thousand, one hundred fifty-five".