21842747 has 4 divisors (see below), whose sum is σ = 21853560. Its totient is φ = 21831936.

The previous prime is 21842719. The next prime is 21842749. The reversal of 21842747 is 74724812.

It is a happy number.

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 21842747 - 2⁶ = 21842683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21842749) 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, 1373 + ... + 6750.

It is an arithmetic number, because the mean of its divisors is an integer number (5463390).

Almost surely, 2^21842747 is an apocalyptic number.

21842747 is a deficient number, since it is larger than the sum of its proper divisors (10813).

21842747 is an equidigital number, since it uses as much as digits as its factorization.

21842747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10812.

The product of its digits is 25088, while the sum is 35.

The square root of 21842747 is about 4673.6224708464. The cubic root of 21842747 is about 279.5347161988.

The spelling of 21842747 in words is "twenty-one million, eight hundred forty-two thousand, seven hundred forty-seven".