1661155507 has 4 divisors (see below), whose sum is σ = 1812169656. Its totient is φ = 1510141360.

The previous prime is 1661155499. The next prime is 1661155511. The reversal of 1661155507 is 7055511661.

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

It is a cyclic number.

It is not a de Polignac number, because 1661155507 - 2³ = 1661155499 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1661155597) 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, 75507058 + ... + 75507079.

It is an arithmetic number, because the mean of its divisors is an integer number (453042414).

Almost surely, 2^1661155507 is an apocalyptic number.

1661155507 is a deficient number, since it is larger than the sum of its proper divisors (151014149).

1661155507 is a wasteful number, since it uses less digits than its factorization.

1661155507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151014148.

The product of its (nonzero) digits is 31500, while the sum is 37.

The square root of 1661155507 is about 40757.2755100240. The cubic root of 1661155507 is about 1184.3228179422.

The spelling of 1661155507 in words is "one billion, six hundred sixty-one million, one hundred fifty-five thousand, five hundred seven".