764021681 has 2 divisors, whose sum is σ = 764021682. Its totient is φ = 764021680.

The previous prime is 764021669. The next prime is 764021693. The reversal of 764021681 is 186120467.

It is a balanced prime because it is at equal distance from previous prime (764021669) and next prime (764021693).

It can be written as a sum of positive squares in only one way, i.e., 561927025 + 202094656 = 23705^2 + 14216^2 .

It is a cyclic number.

It is not a de Polignac number, because 764021681 - 2²⁶ = 696912817 is a prime.

It is a super-2 number, since 2×764021681² = 1167458258076131522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (764021641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 382010840 + 382010841.

It is an arithmetic number, because the mean of its divisors is an integer number (382010841).

Almost surely, 2^764021681 is an apocalyptic number.

It is an amenable number.

764021681 is a deficient number, since it is larger than the sum of its proper divisors (1).

764021681 is an equidigital number, since it uses as much as digits as its factorization.

764021681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 764021681 is about 27640.9421149135. The cubic root of 764021681 is about 914.1873924484.

The spelling of 764021681 in words is "seven hundred sixty-four million, twenty-one thousand, six hundred eighty-one".