15555 has 16 divisors (see below), whose sum is σ = 26784. Its totient is φ = 7680.

The previous prime is 15551. The next prime is 15559. The reversal of 15555 is 55551.

15555 = T₃₄ + T₃₅ + ... + T₅₀.

15555 is nontrivially palindromic in base 16.

It is an interprime number because it is at equal distance from previous prime (15551) and next prime (15559).

It is not a de Polignac number, because 15555 - 2² = 15551 is a prime.

It is a nude number because it is divisible by every one of its digits.

15555 is a modest number, since divided by 555 gives 15 as remainder.

It is a plaindrome in base 10.

It is a nialpdrome in base 5.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (15551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 225 + ... + 285.

It is an arithmetic number, because the mean of its divisors is an integer number (1674).

2¹⁵⁵⁵⁵ is an apocalyptic number.

15555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

15555 is the 102-nd pentagonal number.

15555 is a deficient number, since it is larger than the sum of its proper divisors (11229).

15555 is a wasteful number, since it uses less digits than its factorization.

15555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86.

The product of its digits is 625, while the sum is 21.

The square root of 15555 is about 124.7196856956. The cubic root of 15555 is about 24.9626107764.

Adding to 15555 its sum of digits (21), we get a triangular number (15576 = T₁₇₆).

It can be divided in two parts, 155 and 55, that added together give a triangular number (210 = T₂₀).

The spelling of 15555 in words is "fifteen thousand, five hundred fifty-five".