781077989 has 2 divisors, whose sum is σ = 781077990. Its totient is φ = 781077988.

The previous prime is 781077923. The next prime is 781078021. The reversal of 781077989 is 989770187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 502521889 + 278556100 = 22417^2 + 16690^2 .

It is a cyclic number.

It is not a de Polignac number, because 781077989 - 2¹² = 781073893 is a prime.

It is a super-2 number, since 2×781077989² = 1220165649800568242, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781070989) 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, 390538994 + 390538995.

It is an arithmetic number, because the mean of its divisors is an integer number (390538995).

Almost surely, 2^781077989 is an apocalyptic number.

It is an amenable number.

781077989 is a deficient number, since it is larger than the sum of its proper divisors (1).

781077989 is an equidigital number, since it uses as much as digits as its factorization.

781077989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1778112, while the sum is 56.

The square root of 781077989 is about 27947.7725230473. The cubic root of 781077989 is about 920.9402756782.

The spelling of 781077989 in words is "seven hundred eighty-one million, seventy-seven thousand, nine hundred eighty-nine".