781998397 has 2 divisors, whose sum is σ = 781998398. Its totient is φ = 781998396.

The previous prime is 781998359. The next prime is 781998421. The reversal of 781998397 is 793899187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 775678201 + 6320196 = 27851^2 + 2514^2 .

It is an emirp because it is prime and its reverse (793899187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 781998397 - 2¹¹ = 781996349 is a prime.

It is a super-2 number, since 2×781998397² = 1223042985821139218, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781998097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390999198 + 390999199.

It is an arithmetic number, because the mean of its divisors is an integer number (390999199).

Almost surely, 2^781998397 is an apocalyptic number.

It is an amenable number.

781998397 is a deficient number, since it is larger than the sum of its proper divisors (1).

781998397 is an equidigital number, since it uses as much as digits as its factorization.

781998397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6858432, while the sum is 61.

The square root of 781998397 is about 27964.2342466230. The cubic root of 781998397 is about 921.3018734012.

The spelling of 781998397 in words is "seven hundred eighty-one million, nine hundred ninety-eight thousand, three hundred ninety-seven".