947806921 has 2 divisors, whose sum is σ = 947806922. Its totient is φ = 947806920.

The previous prime is 947806919. The next prime is 947806939. The reversal of 947806921 is 129608749.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 843031225 + 104775696 = 29035^2 + 10236^2 .

It is a cyclic number.

It is not a de Polignac number, because 947806921 - 2¹ = 947806919 is a prime.

Together with 947806919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (947806901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 473903460 + 473903461.

It is an arithmetic number, because the mean of its divisors is an integer number (473903461).

Almost surely, 2^947806921 is an apocalyptic number.

It is an amenable number.

947806921 is a deficient number, since it is larger than the sum of its proper divisors (1).

947806921 is an equidigital number, since it uses as much as digits as its factorization.

947806921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 947806921 is about 30786.4730198183. The cubic root of 947806921 is about 982.2905331628.

The spelling of 947806921 in words is "nine hundred forty-seven million, eight hundred six thousand, nine hundred twenty-one".