21948247 has 4 divisors (see below), whose sum is σ = 21958200. Its totient is φ = 21938296.

The previous prime is 21948229. The next prime is 21948263. The reversal of 21948247 is 74284912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21948247 - 2⁷ = 21948119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21948947) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28 + ... + 6625.

It is an arithmetic number, because the mean of its divisors is an integer number (5489550).

Almost surely, 2^21948247 is an apocalyptic number.

21948247 is a deficient number, since it is larger than the sum of its proper divisors (9953).

21948247 is an equidigital number, since it uses as much as digits as its factorization.

21948247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9952.

The product of its digits is 32256, while the sum is 37.

The square root of 21948247 is about 4684.8956231703. The cubic root of 21948247 is about 279.9840424579.

The spelling of 21948247 in words is "twenty-one million, nine hundred forty-eight thousand, two hundred forty-seven".