921436721 has 2 divisors, whose sum is σ = 921436722. Its totient is φ = 921436720.

The previous prime is 921436717. The next prime is 921436751. The reversal of 921436721 is 127634129.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 834574321 + 86862400 = 28889^2 + 9320^2 .

It is a cyclic number.

It is not a de Polignac number, because 921436721 - 2² = 921436717 is a prime.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (921436751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 460718360 + 460718361.

It is an arithmetic number, because the mean of its divisors is an integer number (460718361).

Almost surely, 2^921436721 is an apocalyptic number.

It is an amenable number.

921436721 is a deficient number, since it is larger than the sum of its proper divisors (1).

921436721 is an equidigital number, since it uses as much as digits as its factorization.

921436721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 35.

The square root of 921436721 is about 30355.1761813368. The cubic root of 921436721 is about 973.0948450722.

The spelling of 921436721 in words is "nine hundred twenty-one million, four hundred thirty-six thousand, seven hundred twenty-one".