21917737 has 2 divisors, whose sum is σ = 21917738. Its totient is φ = 21917736.

The previous prime is 21917699. The next prime is 21917747. The reversal of 21917737 is 73771912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17147881 + 4769856 = 4141^2 + 2184^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21917737 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21917696 and 21917705.

It is not a weakly prime, because it can be changed into another prime (21917747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10958868 + 10958869.

It is an arithmetic number, because the mean of its divisors is an integer number (10958869).

Almost surely, 2^21917737 is an apocalyptic number.

It is an amenable number.

21917737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21917737 is an equidigital number, since it uses as much as digits as its factorization.

21917737 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18522, while the sum is 37.

The square root of 21917737 is about 4681.6382816275. The cubic root of 21917737 is about 279.8542481227.

It can be divided in two parts, 219 and 17737, that added together give a square (17956 = 134²).

The spelling of 21917737 in words is "twenty-one million, nine hundred seventeen thousand, seven hundred thirty-seven".