21754213 has 4 divisors (see below), whose sum is σ = 23427628. Its totient is φ = 20080800.

The previous prime is 21754207. The next prime is 21754283. The reversal of 21754213 is 31245712.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2411809 + 19342404 = 1553^2 + 4398^2 .

It is a cyclic number.

It is not a de Polignac number, because 21754213 - 2⁹ = 21753701 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 (21754283) 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, 836688 + ... + 836713.

It is an arithmetic number, because the mean of its divisors is an integer number (5856907).

Almost surely, 2^21754213 is an apocalyptic number.

It is an amenable number.

21754213 is a deficient number, since it is larger than the sum of its proper divisors (1673415).

21754213 is a wasteful number, since it uses less digits than its factorization.

21754213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1673414.

The product of its digits is 1680, while the sum is 25.

The square root of 21754213 is about 4664.1411856847. The cubic root of 21754213 is about 279.1565305693.

Adding to 21754213 its reverse (31245712), we get a palindrome (52999925).

The spelling of 21754213 in words is "twenty-one million, seven hundred fifty-four thousand, two hundred thirteen".