7764531721 has 2 divisors, whose sum is σ = 7764531722. Its totient is φ = 7764531720.

The previous prime is 7764531713. The next prime is 7764531727. The reversal of 7764531721 is 1271354677.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7742064121 + 22467600 = 87989^2 + 4740^2 .

It is a cyclic number.

It is not a de Polignac number, because 7764531721 - 2³ = 7764531713 is a prime.

It is not a weakly prime, because it can be changed into another prime (7764531727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3882265860 + 3882265861.

It is an arithmetic number, because the mean of its divisors is an integer number (3882265861).

Almost surely, 2^7764531721 is an apocalyptic number.

It is an amenable number.

7764531721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7764531721 is an equidigital number, since it uses as much as digits as its factorization.

7764531721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 246960, while the sum is 43.

The square root of 7764531721 is about 88116.5802843029. The cubic root of 7764531721 is about 1980.1819137863.

The spelling of 7764531721 in words is "seven billion, seven hundred sixty-four million, five hundred thirty-one thousand, seven hundred twenty-one".