2155661505 has 24 divisors (see below), whose sum is σ = 3874870272. Its totient is φ = 1149685488.

The previous prime is 2155661503. The next prime is 2155661561. The reversal of 2155661505 is 5051665512.

It is not a de Polignac number, because 2155661505 - 2¹ = 2155661503 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 2155661505.

It is not an unprimeable number, because it can be changed into a prime (2155661503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 885889 + ... + 888318.

It is an arithmetic number, because the mean of its divisors is an integer number (161452928).

Almost surely, 2^2155661505 is an apocalyptic number.

It is an amenable number.

2155661505 is a deficient number, since it is larger than the sum of its proper divisors (1719208767).

2155661505 is an equidigital number, since it uses as much as digits as its factorization.

2155661505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1774227 (or 1774215 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 36.

The square root of 2155661505 is about 46429.1019189473. The cubic root of 2155661505 is about 1291.7947705805.

The spelling of 2155661505 in words is "two billion, one hundred fifty-five million, six hundred sixty-one thousand, five hundred five".