21954047 has 2 divisors, whose sum is σ = 21954048. Its totient is φ = 21954046.

The previous prime is 21954019. The next prime is 21954059. The reversal of 21954047 is 74045912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21954047 - 2⁸ = 21953791 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21954547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10977023 + 10977024.

It is an arithmetic number, because the mean of its divisors is an integer number (10977024).

Almost surely, 2^21954047 is an apocalyptic number.

21954047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21954047 is an equidigital number, since it uses as much as digits as its factorization.

21954047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21954047 is about 4685.5145928702. The cubic root of 21954047 is about 280.0087029608.

Adding to 21954047 its reverse (74045912), we get a palindrome (95999959).

The spelling of 21954047 in words is "twenty-one million, nine hundred fifty-four thousand, forty-seven".