21343247 has 4 divisors (see below), whose sum is σ = 21863856. Its totient is φ = 20822640.

The previous prime is 21343243. The next prime is 21343249. The reversal of 21343247 is 74234312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21343247 - 2² = 21343243 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 (21343243) 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, 260243 + ... + 260324.

It is an arithmetic number, because the mean of its divisors is an integer number (5465964).

Almost surely, 2^21343247 is an apocalyptic number.

21343247 is a deficient number, since it is larger than the sum of its proper divisors (520609).

21343247 is an equidigital number, since it uses as much as digits as its factorization.

21343247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520608.

The product of its digits is 4032, while the sum is 26.

The square root of 21343247 is about 4619.8752147650. The cubic root of 21343247 is about 277.3874640407.

Adding to 21343247 its reverse (74234312), we get a palindrome (95577559).

The spelling of 21343247 in words is "twenty-one million, three hundred forty-three thousand, two hundred forty-seven".