921742721 has 2 divisors, whose sum is σ = 921742722. Its totient is φ = 921742720.

The previous prime is 921742697. The next prime is 921742741. The reversal of 921742721 is 127247129.

921742721 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., 650811121 + 270931600 = 25511^2 + 16460^2 .

It is a cyclic number.

It is not a de Polignac number, because 921742721 - 2¹⁰ = 921741697 is a prime.

It is not a weakly prime, because it can be changed into another prime (921742741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 460871360 + 460871361.

It is an arithmetic number, because the mean of its divisors is an integer number (460871361).

Almost surely, 2^921742721 is an apocalyptic number.

It is an amenable number.

921742721 is a deficient number, since it is larger than the sum of its proper divisors (1).

921742721 is an equidigital number, since it uses as much as digits as its factorization.

921742721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 35.

The square root of 921742721 is about 30360.2160894813. The cubic root of 921742721 is about 973.2025515339.

The spelling of 921742721 in words is "nine hundred twenty-one million, seven hundred forty-two thousand, seven hundred twenty-one".