155505551 has 4 divisors (see below), whose sum is σ = 158439672. Its totient is φ = 152571432.

The previous prime is 155505547. The next prime is 155505577.

155505551 is nontrivially palindromic in base 10.

155505551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 155505551 - 2² = 155505547 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 (155505541) 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, 1466981 + ... + 1467086.

It is an arithmetic number, because the mean of its divisors is an integer number (39609918).

Almost surely, 2^155505551 is an apocalyptic number.

155505551 is a deficient number, since it is larger than the sum of its proper divisors (2934121).

155505551 is an equidigital number, since it uses as much as digits as its factorization.

155505551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2934120.

The product of its (nonzero) digits is 15625, while the sum is 32.

The square root of 155505551 is about 12470.1864861757. The cubic root of 155505551 is about 537.7519147971.

The spelling of 155505551 in words is "one hundred fifty-five million, five hundred five thousand, five hundred fifty-one".