551915561 has 4 divisors (see below), whose sum is σ = 552167172. Its totient is φ = 551663952.

The previous prime is 551915543. The next prime is 551915563. The reversal of 551915561 is 165519155.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 475458025 + 76457536 = 21805^2 + 8744^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-551915561 is a prime.

It is a super-2 number, since 2×551915561² = 609221572947889442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (551915563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122486 + ... + 126911.

It is an arithmetic number, because the mean of its divisors is an integer number (138041793).

Almost surely, 2^551915561 is an apocalyptic number.

It is an amenable number.

551915561 is a deficient number, since it is larger than the sum of its proper divisors (251611).

551915561 is a wasteful number, since it uses less digits than its factorization.

551915561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251610.

The product of its digits is 33750, while the sum is 38.

The square root of 551915561 is about 23492.8831989605. The cubic root of 551915561 is about 820.2713562561.

The spelling of 551915561 in words is "five hundred fifty-one million, nine hundred fifteen thousand, five hundred sixty-one".