945165721 has 2 divisors, whose sum is σ = 945165722. Its totient is φ = 945165720.

The previous prime is 945165719. The next prime is 945165731. The reversal of 945165721 is 127561549.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 733055625 + 212110096 = 27075^2 + 14564^2 .

It is an emirp because it is prime and its reverse (127561549) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 945165721 - 2¹ = 945165719 is a prime.

Together with 945165719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (945165731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 472582860 + 472582861.

It is an arithmetic number, because the mean of its divisors is an integer number (472582861).

Almost surely, 2^945165721 is an apocalyptic number.

It is an amenable number.

945165721 is a deficient number, since it is larger than the sum of its proper divisors (1).

945165721 is an equidigital number, since it uses as much as digits as its factorization.

945165721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 40.

The square root of 945165721 is about 30743.5476319829. The cubic root of 945165721 is about 981.3772531302.

The spelling of 945165721 in words is "nine hundred forty-five million, one hundred sixty-five thousand, seven hundred twenty-one".