21154442 has 8 divisors (see below), whose sum is σ = 32505732. Its totient is φ = 10319200.

The previous prime is 21154403. The next prime is 21154447. The reversal of 21154442 is 24445112.

It can be written as a sum of positive squares in 2 ways, for example, as 20693401 + 461041 = 4549^2 + 679^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21154447) 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, 128909 + ... + 129072.

Almost surely, 2^21154442 is an apocalyptic number.

21154442 is a deficient number, since it is larger than the sum of its proper divisors (11351290).

21154442 is a wasteful number, since it uses less digits than its factorization.

21154442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258024.

The product of its digits is 1280, while the sum is 23.

The square root of 21154442 is about 4599.3958298890. The cubic root of 21154442 is about 276.5671056741.

Adding to 21154442 its reverse (24445112), we get a palindrome (45599554).

The spelling of 21154442 in words is "twenty-one million, one hundred fifty-four thousand, four hundred forty-two".