493991989 has 2 divisors, whose sum is σ = 493991990. Its totient is φ = 493991988.

The previous prime is 493991987. The next prime is 493992019. The reversal of 493991989 is 989199394.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 493595089 + 396900 = 22217^2 + 630^2 .

It is a cyclic number.

It is not a de Polignac number, because 493991989 - 2¹ = 493991987 is a prime.

It is a super-2 number, since 2×493991989² = 488056170392352242, which contains 22 as substring.

Together with 493991987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (493991987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 246995994 + 246995995.

It is an arithmetic number, because the mean of its divisors is an integer number (246995995).

Almost surely, 2^493991989 is an apocalyptic number.

It is an amenable number.

493991989 is a deficient number, since it is larger than the sum of its proper divisors (1).

493991989 is an equidigital number, since it uses as much as digits as its factorization.

493991989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5668704, while the sum is 61.

The square root of 493991989 is about 22225.9305541973. The cubic root of 493991989 is about 790.5086661601.

The spelling of 493991989 in words is "four hundred ninety-three million, nine hundred ninety-one thousand, nine hundred eighty-nine".