21240154 has 8 divisors (see below), whose sum is σ = 34311060. Its totient is φ = 9803136.

The previous prime is 21240133. The next prime is 21240161. The reversal of 21240154 is 45104212.

It can be written as a sum of positive squares in 2 ways, for example, as 19123129 + 2117025 = 4373^2 + 1455^2 .

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

It is a super-2 number, since 2×21240154² = 902288283887432, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 408439 + ... + 408490.

Almost surely, 2^21240154 is an apocalyptic number.

21240154 is a deficient number, since it is larger than the sum of its proper divisors (13070906).

21240154 is a wasteful number, since it uses less digits than its factorization.

21240154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816944.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21240154 is about 4608.7041562678. The cubic root of 21240154 is about 276.9401270327.

Adding to 21240154 its reverse (45104212), we get a palindrome (66344366).

The spelling of 21240154 in words is "twenty-one million, two hundred forty thousand, one hundred fifty-four".