21494772 has 54 divisors (see below), whose sum is σ = 58851702. Its totient is φ = 6611904.

The previous prime is 21494729. The next prime is 21494779. The reversal of 21494772 is 27749412.

It can be written as a sum of positive squares in 3 ways, for example, as 646416 + 20848356 = 804^2 + 4566^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21494779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 4318 + ... + 7850.

Almost surely, 2^21494772 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21494772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29425851).

21494772 is an abundant number, since it is smaller than the sum of its proper divisors (37356930).

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

21494772 is a wasteful number, since it uses less digits than its factorization.

21494772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3569 (or 3551 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21494772 is about 4636.2454637346. The cubic root of 21494772 is about 278.0423481542.

The spelling of 21494772 in words is "twenty-one million, four hundred ninety-four thousand, seven hundred seventy-two".