21115454 has 4 divisors (see below), whose sum is σ = 31673184. Its totient is φ = 10557726.

The previous prime is 21115453. The next prime is 21115511. The reversal of 21115454 is 45451112.

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

It is a super-2 number, since 2×21115454² = 891724795252232, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5278862 + ... + 5278865.

It is an arithmetic number, because the mean of its divisors is an integer number (7918296).

Almost surely, 2^21115454 is an apocalyptic number.

21115454 is a deficient number, since it is larger than the sum of its proper divisors (10557730).

21115454 is a wasteful number, since it uses less digits than its factorization.

21115454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10557729.

The product of its digits is 800, while the sum is 23.

The square root of 21115454 is about 4595.1554924725. The cubic root of 21115454 is about 276.3970952117.

Adding to 21115454 its reverse (45451112), we get a palindrome (66566566).

The spelling of 21115454 in words is "twenty-one million, one hundred fifteen thousand, four hundred fifty-four".