561491993 has 2 divisors, whose sum is σ = 561491994. Its totient is φ = 561491992.

The previous prime is 561491989. The next prime is 561491999. The reversal of 561491993 is 399194165.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 515834944 + 45657049 = 22712^2 + 6757^2 .

It is a cyclic number.

It is not a de Polignac number, because 561491993 - 2² = 561491989 is a prime.

It is a super-2 number, since 2×561491993² = 630546516406224098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (561491999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280745996 + 280745997.

It is an arithmetic number, because the mean of its divisors is an integer number (280745997).

Almost surely, 2^561491993 is an apocalyptic number.

It is an amenable number.

561491993 is a deficient number, since it is larger than the sum of its proper divisors (1).

561491993 is an equidigital number, since it uses as much as digits as its factorization.

561491993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 262440, while the sum is 47.

The square root of 561491993 is about 23695.8222689148. The cubic root of 561491993 is about 824.9884261615.

The spelling of 561491993 in words is "five hundred sixty-one million, four hundred ninety-one thousand, nine hundred ninety-three".