155551551 has 4 divisors (see below), whose sum is σ = 207402072. Its totient is φ = 103701032.

The previous prime is 155551549. The next prime is 155551577. The reversal of 155551551 is 155155551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 155155551 = 3 ⋅51718517.

It is a cyclic number.

It is not a de Polignac number, because 155551551 - 2¹ = 155551549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155551541) 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, 25925256 + ... + 25925261.

It is an arithmetic number, because the mean of its divisors is an integer number (51850518).

Almost surely, 2^155551551 is an apocalyptic number.

155551551 is a deficient number, since it is larger than the sum of its proper divisors (51850521).

155551551 is an equidigital number, since it uses as much as digits as its factorization.

155551551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51850520.

The product of its digits is 15625, while the sum is 33.

The square root of 155551551 is about 12472.0307488396. The cubic root of 155551551 is about 537.8049335891.

The spelling of 155551551 in words is "one hundred fifty-five million, five hundred fifty-one thousand, five hundred fifty-one".