561155551 has 4 divisors (see below), whose sum is σ = 612169704. Its totient is φ = 510141400.

The previous prime is 561155501. The next prime is 561155563. The reversal of 561155551 is 155551165.

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 561155551 - 2¹¹ = 561153503 is a prime.

It is a super-2 number, since 2×561155551² = 629791104836227202, 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 (561155501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25507060 + ... + 25507081.

It is an arithmetic number, because the mean of its divisors is an integer number (153042426).

Almost surely, 2^561155551 is an apocalyptic number.

561155551 is a deficient number, since it is larger than the sum of its proper divisors (51014153).

561155551 is a wasteful number, since it uses less digits than its factorization.

561155551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51014152.

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

The square root of 561155551 is about 23688.7220212488. The cubic root of 561155551 is about 824.8236175115.

The spelling of 561155551 in words is "five hundred sixty-one million, one hundred fifty-five thousand, five hundred fifty-one".