556751981 has 2 divisors, whose sum is σ = 556751982. Its totient is φ = 556751980.

The previous prime is 556751959. The next prime is 556751983. The reversal of 556751981 is 189157655.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 539818756 + 16933225 = 23234^2 + 4115^2 .

It is a cyclic number.

It is not a de Polignac number, because 556751981 - 2²⁶ = 489643117 is a prime.

It is a super-2 number, since 2×556751981² = 619945536694848722, which contains 22 as substring.

Together with 556751983, 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 (556751983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 278375990 + 278375991.

It is an arithmetic number, because the mean of its divisors is an integer number (278375991).

Almost surely, 2^556751981 is an apocalyptic number.

It is an amenable number.

556751981 is a deficient number, since it is larger than the sum of its proper divisors (1).

556751981 is an equidigital number, since it uses as much as digits as its factorization.

556751981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 378000, while the sum is 47.

The square root of 556751981 is about 23595.5924062101. The cubic root of 556751981 is about 822.6603960987.

The spelling of 556751981 in words is "five hundred fifty-six million, seven hundred fifty-one thousand, nine hundred eighty-one".