551661557 has 2 divisors, whose sum is σ = 551661558. Its totient is φ = 551661556.

The previous prime is 551661553. The next prime is 551661559. The reversal of 551661557 is 755166155.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 320803921 + 230857636 = 17911^2 + 15194^2 .

It is a cyclic number.

It is not a de Polignac number, because 551661557 - 2² = 551661553 is a prime.

Together with 551661559, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (551661553) 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 as a sum of consecutive naturals, namely, 275830778 + 275830779.

It is an arithmetic number, because the mean of its divisors is an integer number (275830779).

Almost surely, 2^551661557 is an apocalyptic number.

It is an amenable number.

551661557 is a deficient number, since it is larger than the sum of its proper divisors (1).

551661557 is an equidigital number, since it uses as much as digits as its factorization.

551661557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 157500, while the sum is 41.

The square root of 551661557 is about 23487.4765992433. The cubic root of 551661557 is about 820.1455011488.

The spelling of 551661557 in words is "five hundred fifty-one million, six hundred sixty-one thousand, five hundred fifty-seven".