766681021 has 2 divisors, whose sum is σ = 766681022. Its totient is φ = 766681020.

The previous prime is 766681007. The next prime is 766681063. The reversal of 766681021 is 120186667.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 570540996 + 196140025 = 23886^2 + 14005^2 .

It is a cyclic number.

It is not a de Polignac number, because 766681021 - 2¹⁹ = 766156733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (766681121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 383340510 + 383340511.

It is an arithmetic number, because the mean of its divisors is an integer number (383340511).

Almost surely, 2^766681021 is an apocalyptic number.

It is an amenable number.

766681021 is a deficient number, since it is larger than the sum of its proper divisors (1).

766681021 is an equidigital number, since it uses as much as digits as its factorization.

766681021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 766681021 is about 27689.0054173132. The cubic root of 766681021 is about 915.2468387565.

The spelling of 766681021 in words is "seven hundred sixty-six million, six hundred eighty-one thousand, twenty-one".