781025261 has 2 divisors, whose sum is σ = 781025262. Its totient is φ = 781025260.

The previous prime is 781025257. The next prime is 781025299. The reversal of 781025261 is 162520187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 467381161 + 313644100 = 21619^2 + 17710^2 .

It is a cyclic number.

It is not a de Polignac number, because 781025261 - 2² = 781025257 is a prime.

It is a super-2 number, since 2×781025261² = 1220000916640236242, 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 (781025251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390512630 + 390512631.

It is an arithmetic number, because the mean of its divisors is an integer number (390512631).

Almost surely, 2^781025261 is an apocalyptic number.

It is an amenable number.

781025261 is a deficient number, since it is larger than the sum of its proper divisors (1).

781025261 is an equidigital number, since it uses as much as digits as its factorization.

781025261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 781025261 is about 27946.8291761337. The cubic root of 781025261 is about 920.9195519979.

The spelling of 781025261 in words is "seven hundred eighty-one million, twenty-five thousand, two hundred sixty-one".