21154240 has 28 divisors (see below), whose sum is σ = 50374296. Its totient is φ = 8461568.

The previous prime is 21154207. The next prime is 21154283. The reversal of 21154240 is 4245112.

It is a congruent number.

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, 32734 + ... + 33373.

It is an arithmetic number, because the mean of its divisors is an integer number (1799082).

Almost surely, 2^21154240 is an apocalyptic number.

21154240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21154240 is an abundant number, since it is smaller than the sum of its proper divisors (29220056).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21154240 is an equidigital number, since it uses as much as digits as its factorization.

21154240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66124 (or 66114 counting only the distinct ones).

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

The square root of 21154240 is about 4599.3738704306. The cubic root of 21154240 is about 276.5662253746.

Adding to 21154240 its reverse (4245112), we get a palindrome (25399352).

The spelling of 21154240 in words is "twenty-one million, one hundred fifty-four thousand, two hundred forty".