21243455 has 8 divisors (see below), whose sum is σ = 26991792. Its totient is φ = 15995008.

The previous prime is 21243437. The next prime is 21243473. The reversal of 21243455 is 55434212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21243437) and next prime (21243473).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21243455 - 2²⁰ = 20194879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124877 + ... + 125046.

It is an arithmetic number, because the mean of its divisors is an integer number (3373974).

Almost surely, 2^21243455 is an apocalyptic number.

21243455 is a deficient number, since it is larger than the sum of its proper divisors (5748337).

21243455 is a wasteful number, since it uses less digits than its factorization.

21243455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249945.

The product of its digits is 4800, while the sum is 26.

The square root of 21243455 is about 4609.0622690521. The cubic root of 21243455 is about 276.9544730053.

Adding to 21243455 its reverse (55434212), we get a palindrome (76677667).

The spelling of 21243455 in words is "twenty-one million, two hundred forty-three thousand, four hundred fifty-five".