21494440 has 48 divisors (see below), whose sum is σ = 53170740. Its totient is φ = 7814400.

The previous prime is 21494437. The next prime is 21494441. The reversal of 21494440 is 4449412.

It can be written as a sum of positive squares in 2 ways, for example, as 21141604 + 352836 = 4598^2 + 594^2 .

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21494399 and 21494408.

It is not an unprimeable number, because it can be changed into a prime (21494441) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2620 + ... + 7060.

Almost surely, 2^21494440 is an apocalyptic number.

21494440 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 21494440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26585370).

21494440 is an abundant number, since it is smaller than the sum of its proper divisors (31676300).

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

21494440 is a wasteful number, since it uses less digits than its factorization.

21494440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4474 (or 4459 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 21494440 is about 4636.2096587622. The cubic root of 21494440 is about 278.0409166351.

The spelling of 21494440 in words is "twenty-one million, four hundred ninety-four thousand, four hundred forty".