21994547 has 2 divisors, whose sum is σ = 21994548. Its totient is φ = 21994546.

The previous prime is 21994529. The next prime is 21994561. The reversal of 21994547 is 74549912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21994547 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21994597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10997273 + 10997274.

It is an arithmetic number, because the mean of its divisors is an integer number (10997274).

Almost surely, 2^21994547 is an apocalyptic number.

21994547 is a deficient number, since it is larger than the sum of its proper divisors (1).

21994547 is an equidigital number, since it uses as much as digits as its factorization.

21994547 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The square root of 21994547 is about 4689.8344320455. The cubic root of 21994547 is about 280.1807803639.

The spelling of 21994547 in words is "twenty-one million, nine hundred ninety-four thousand, five hundred forty-seven".