155551561 has 8 divisors (see below), whose sum is σ = 170322048. Its totient is φ = 140886000.

The previous prime is 155551549. The next prime is 155551577. The reversal of 155551561 is 165155551.

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 155551561 - 2⁷ = 155551433 is a prime.

It is a Duffinian 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 7 ways as a sum of consecutive naturals, for example, 23110 + ... + 29071.

It is an arithmetic number, because the mean of its divisors is an integer number (21290256).

Almost surely, 2^155551561 is an apocalyptic number.

155551561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

155551561 is a deficient number, since it is larger than the sum of its proper divisors (14770487).

155551561 is a wasteful number, since it uses less digits than its factorization.

155551561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52463.

The product of its digits is 18750, while the sum is 34.

The square root of 155551561 is about 12472.0311497366. The cubic root of 155551561 is about 537.8049451138.

The spelling of 155551561 in words is "one hundred fifty-five million, five hundred fifty-one thousand, five hundred sixty-one".