551981 has 2 divisors, whose sum is σ = 551982. Its totient is φ = 551980.

The previous prime is 551963. The next prime is 552001. The reversal of 551981 is 189155.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 538756 + 13225 = 734^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 551981 - 2⁶ = 551917 is a prime.

It is a super-2 number, since 2×551981² = 609366048722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (551911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 275990 + 275991.

It is an arithmetic number, because the mean of its divisors is an integer number (275991).

2⁵⁵¹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

551981 is a deficient number, since it is larger than the sum of its proper divisors (1).

551981 is an equidigital number, since it uses as much as digits as its factorization.

551981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 29.

The square root of 551981 is about 742.9542381601. The cubic root of 551981 is about 82.0303774027.

The spelling of 551981 in words is "five hundred fifty-one thousand, nine hundred eighty-one".