21994897 has 2 divisors, whose sum is σ = 21994898. Its totient is φ = 21994896.

The previous prime is 21994867. The next prime is 21994981. The reversal of 21994897 is 79849912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19989841 + 2005056 = 4471^2 + 1416^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21994897 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21994897.

It is not a weakly prime, because it can be changed into another prime (21994807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10997448 + 10997449.

It is an arithmetic number, because the mean of its divisors is an integer number (10997449).

Almost surely, 2^21994897 is an apocalyptic number.

It is an amenable number.

21994897 is a deficient number, since it is larger than the sum of its proper divisors (1).

21994897 is an equidigital number, since it uses as much as digits as its factorization.

21994897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 49.

The square root of 21994897 is about 4689.8717466472. The cubic root of 21994897 is about 280.1822665316.

The spelling of 21994897 in words is "twenty-one million, nine hundred ninety-four thousand, eight hundred ninety-seven".