21947633 has 2 divisors, whose sum is σ = 21947634. Its totient is φ = 21947632.

The previous prime is 21947593. The next prime is 21947657. The reversal of 21947633 is 33674912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17247409 + 4700224 = 4153^2 + 2168^2 .

It is a cyclic number.

It is not a de Polignac number, because 21947633 - 2²⁰ = 20899057 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21947593 and 21947602.

It is not a weakly prime, because it can be changed into another prime (21947533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973816 + 10973817.

It is an arithmetic number, because the mean of its divisors is an integer number (10973817).

Almost surely, 2^21947633 is an apocalyptic number.

It is an amenable number.

21947633 is a deficient number, since it is larger than the sum of its proper divisors (1).

21947633 is an equidigital number, since it uses as much as digits as its factorization.

21947633 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 35.

The square root of 21947633 is about 4684.8300929703. The cubic root of 21947633 is about 279.9814315918.

The spelling of 21947633 in words is "twenty-one million, nine hundred forty-seven thousand, six hundred thirty-three".