21849420 has 96 divisors (see below), whose sum is σ = 66963456. Its totient is φ = 5299200.

The previous prime is 21849419. The next prime is 21849427. The reversal of 21849420 is 2494812.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21849427) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 31275 + ... + 31965.

It is an arithmetic number, because the mean of its divisors is an integer number (697536).

Almost surely, 2^21849420 is an apocalyptic number.

21849420 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 21849420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33481728).

21849420 is an abundant number, since it is smaller than the sum of its proper divisors (45114036).

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

21849420 is a wasteful number, since it uses less digits than its factorization.

21849420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751 (or 749 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 21849420 is about 4674.3363165267. The cubic root of 21849420 is about 279.5631794264.

Subtracting from 21849420 its product of nonzero digits (4608), we obtain a palindrome (21844812).

The spelling of 21849420 in words is "twenty-one million, eight hundred forty-nine thousand, four hundred twenty".