781148989 has 2 divisors, whose sum is σ = 781148990. Its totient is φ = 781148988.

The previous prime is 781148987. The next prime is 781149001. The reversal of 781148989 is 989841187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 520068025 + 261080964 = 22805^2 + 16158^2 .

It is a cyclic number.

It is not a de Polignac number, because 781148989 - 2¹ = 781148987 is a prime.

It is a super-2 number, since 2×781148989² = 1220387486031444242, which contains 22 as substring.

Together with 781148987, 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 (781148987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390574494 + 390574495.

It is an arithmetic number, because the mean of its divisors is an integer number (390574495).

Almost surely, 2^781148989 is an apocalyptic number.

It is an amenable number.

781148989 is a deficient number, since it is larger than the sum of its proper divisors (1).

781148989 is an equidigital number, since it uses as much as digits as its factorization.

781148989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1161216, while the sum is 55.

The square root of 781148989 is about 27949.0427206371. The cubic root of 781148989 is about 920.9681793273.

The spelling of 781148989 in words is "seven hundred eighty-one million, one hundred forty-eight thousand, nine hundred eighty-nine".