1679457781 has 2 divisors, whose sum is σ = 1679457782. Its totient is φ = 1679457780.

The previous prime is 1679457763. The next prime is 1679457797. The reversal of 1679457781 is 1877549761.

It is the 16731-st star number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1631432881 + 48024900 = 40391^2 + 6930^2 .

It is a cyclic number.

It is not a de Polignac number, because 1679457781 - 2²⁵ = 1645903349 is a prime.

It is a super-2 number, since 2×1679457781² = 5641156876322887922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1679457701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 839728890 + 839728891.

It is an arithmetic number, because the mean of its divisors is an integer number (839728891).

Almost surely, 2^1679457781 is an apocalyptic number.

1679457781 is the 23661-st hex number.

It is an amenable number.

1679457781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1679457781 is an equidigital number, since it uses as much as digits as its factorization.

1679457781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2963520, while the sum is 55.

The square root of 1679457781 is about 40981.1881355336. The cubic root of 1679457781 is about 1188.6564836395.

The spelling of 1679457781 in words is "one billion, six hundred seventy-nine million, four hundred fifty-seven thousand, seven hundred eighty-one".