1555166661 has 8 divisors (see below), whose sum is σ = 2085012384. Its totient is φ = 1031049360.

The previous prime is 1555166653. The next prime is 1555166699. The reversal of 1555166661 is 1666615551.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1555166661 - 2³ = 1555166653 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1555166461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1431471 + ... + 1432556.

It is an arithmetic number, because the mean of its divisors is an integer number (260626548).

Almost surely, 2^1555166661 is an apocalyptic number.

It is an amenable number.

1555166661 is a deficient number, since it is larger than the sum of its proper divisors (529845723).

1555166661 is a wasteful number, since it uses less digits than its factorization.

1555166661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2864211.

The product of its digits is 162000, while the sum is 42.

The square root of 1555166661 is about 39435.6014408301. The cubic root of 1555166661 is about 1158.5789825451.

The spelling of 1555166661 in words is "one billion, five hundred fifty-five million, one hundred sixty-six thousand, six hundred sixty-one".