155551 has 8 divisors (see below), whose sum is σ = 172800. Its totient is φ = 138840.

The previous prime is 155539. The next prime is 155557.

155551 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is not a de Polignac number, because 155551 - 2⁷ = 155423 is a prime.

It is a super-2 number, since 2×155551² = 48392227202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 780 + ... + 958.

It is an arithmetic number, because the mean of its divisors is an integer number (21600).

2¹⁵⁵⁵⁵¹ is an apocalyptic number.

155551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

155551 is a deficient number, since it is larger than the sum of its proper divisors (17249).

155551 is a wasteful number, since it uses less digits than its factorization.

155551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269.

The product of its digits is 625, while the sum is 22.

The square root of 155551 is about 394.3995436103. The cubic root of 155551 is about 53.7804298578.

The spelling of 155551 in words is "one hundred fifty-five thousand, five hundred fifty-one".