2921697721 has 2 divisors, whose sum is σ = 2921697722. Its totient is φ = 2921697720.

The previous prime is 2921697683. The next prime is 2921697731. The reversal of 2921697721 is 1277961292.

It is a happy number.

2921697721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1487182096 + 1434515625 = 38564^2 + 37875^2 .

It is a cyclic number.

It is not a de Polignac number, because 2921697721 - 2²¹ = 2919600569 is a prime.

It is not a weakly prime, because it can be changed into another prime (2921697731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1460848860 + 1460848861.

It is an arithmetic number, because the mean of its divisors is an integer number (1460848861).

Almost surely, 2^2921697721 is an apocalyptic number.

It is an amenable number.

2921697721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2921697721 is an equidigital number, since it uses as much as digits as its factorization.

2921697721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 190512, while the sum is 46.

The square root of 2921697721 is about 54052.7309300834. The cubic root of 2921697721 is about 1429.5908525136.

The spelling of 2921697721 in words is "two billion, nine hundred twenty-one million, six hundred ninety-seven thousand, seven hundred twenty-one".