781428517 has 2 divisors, whose sum is σ = 781428518. Its totient is φ = 781428516.

The previous prime is 781428469. The next prime is 781428539. The reversal of 781428517 is 715824187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 781426116 + 2401 = 27954^2 + 49^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-781428517 is a prime.

It is a super-2 number, since 2×781428517² = 1221261054361638578, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781428547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390714258 + 390714259.

It is an arithmetic number, because the mean of its divisors is an integer number (390714259).

Almost surely, 2^781428517 is an apocalyptic number.

It is an amenable number.

781428517 is a deficient number, since it is larger than the sum of its proper divisors (1).

781428517 is an equidigital number, since it uses as much as digits as its factorization.

781428517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 125440, while the sum is 43.

The square root of 781428517 is about 27954.0429455204. The cubic root of 781428517 is about 921.0780199577.

The spelling of 781428517 in words is "seven hundred eighty-one million, four hundred twenty-eight thousand, five hundred seventeen".