13555661 has 4 divisors (see below), whose sum is σ = 15492192. Its totient is φ = 11619132.

The previous prime is 13555657. The next prime is 13555669. The reversal of 13555661 is 16655531.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16655531 = 47 ⋅354373.

It is not a de Polignac number, because 13555661 - 2² = 13555657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13555669) 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, 968255 + ... + 968268.

It is an arithmetic number, because the mean of its divisors is an integer number (3873048).

Almost surely, 2^13555661 is an apocalyptic number.

It is an amenable number.

13555661 is a deficient number, since it is larger than the sum of its proper divisors (1936531).

13555661 is an equidigital number, since it uses as much as digits as its factorization.

13555661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1936530.

The product of its digits is 13500, while the sum is 32.

The square root of 13555661 is about 3681.8013254384. The cubic root of 13555661 is about 238.4369547404.

The spelling of 13555661 in words is "thirteen million, five hundred fifty-five thousand, six hundred sixty-one".