21244740 has 48 divisors (see below), whose sum is σ = 64895040. Its totient is φ = 5150080.

The previous prime is 21244723. The next prime is 21244757. The reversal of 21244740 is 4744212.

It is an interprime number because it is at equal distance from previous prime (21244723) and next prime (21244757).

It is a self number, because there is not a number n which added to its sum of digits gives 21244740.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15435 + ... + 16754.

It is an arithmetic number, because the mean of its divisors is an integer number (1351980).

Almost surely, 2^21244740 is an apocalyptic number.

21244740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21244740 is an abundant number, since it is smaller than the sum of its proper divisors (43650300).

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

21244740 is a wasteful number, since it uses less digits than its factorization.

21244740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32212 (or 32210 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 24.

The square root of 21244740 is about 4609.2016662325. The cubic root of 21244740 is about 276.9600571460.

Adding to 21244740 its reverse (4744212), we get a palindrome (25988952).

The spelling of 21244740 in words is "twenty-one million, two hundred forty-four thousand, seven hundred forty".