21154220 has 48 divisors (see below), whose sum is σ = 47174400. Its totient is φ = 7945920.

The previous prime is 21154207. The next prime is 21154283. The reversal of 21154220 is 2245112.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 67865 + ... + 68175.

It is an arithmetic number, because the mean of its divisors is an integer number (982800).

Almost surely, 2^21154220 is an apocalyptic number.

21154220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21154220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23587200).

21154220 is an abundant number, since it is smaller than the sum of its proper divisors (26020180).

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

21154220 is a wasteful number, since it uses less digits than its factorization.

21154220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 518 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21154220 is about 4599.3716962211. The cubic root of 21154220 is about 276.5661382159.

Adding to 21154220 its reverse (2245112), we get a palindrome (23399332).

The spelling of 21154220 in words is "twenty-one million, one hundred fifty-four thousand, two hundred twenty".