21247996 has 48 divisors (see below), whose sum is σ = 46771200. Its totient is φ = 8205120.

The previous prime is 21247991. The next prime is 21247999. The reversal of 21247996 is 69974212.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45661 + ... + 46123.

It is an arithmetic number, because the mean of its divisors is an integer number (974400).

Almost surely, 2^21247996 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 21247996, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23385600).

21247996 is an abundant number, since it is smaller than the sum of its proper divisors (25523204).

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

21247996 is a wasteful number, since it uses less digits than its factorization.

21247996 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 632 counting only the distinct ones).

The product of its digits is 54432, while the sum is 40.

The square root of 21247996 is about 4609.5548592028. The cubic root of 21247996 is about 276.9742055247.

The spelling of 21247996 in words is "twenty-one million, two hundred forty-seven thousand, nine hundred ninety-six".