21344731 has 4 divisors (see below), whose sum is σ = 21357000. Its totient is φ = 21332464.

The previous prime is 21344717. The next prime is 21344767. The reversal of 21344731 is 13744312.

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 21344731 - 2⁵ = 21344699 is a prime.

It is a super-2 number, since 2×21344731² = 911195082924722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21344696 and 21344705.

It is not an unprimeable number, because it can be changed into a prime (21344711) 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, 2986 + ... + 7183.

It is an arithmetic number, because the mean of its divisors is an integer number (5339250).

Almost surely, 2^21344731 is an apocalyptic number.

21344731 is a deficient number, since it is larger than the sum of its proper divisors (12269).

21344731 is a wasteful number, since it uses less digits than its factorization.

21344731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12268.

The product of its digits is 2016, while the sum is 25.

The square root of 21344731 is about 4620.0358223719. The cubic root of 21344731 is about 277.3938928260.

It can be divided in two parts, 213 and 44731, that added together give a palindrome (44944).

The spelling of 21344731 in words is "twenty-one million, three hundred forty-four thousand, seven hundred thirty-one".