21719724 has 48 divisors (see below), whose sum is σ = 56471520. Its totient is φ = 6451200.

The previous prime is 21719699. The next prime is 21719741. The reversal of 21719724 is 42791712.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2124 + ... + 6924.

It is an arithmetic number, because the mean of its divisors is an integer number (1176490).

Almost surely, 2^21719724 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 21719724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28235760).

21719724 is an abundant number, since it is smaller than the sum of its proper divisors (34751796).

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

21719724 is a wasteful number, since it uses less digits than its factorization.

21719724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4850 (or 4848 counting only the distinct ones).

The product of its digits is 7056, while the sum is 33.

The square root of 21719724 is about 4660.4424682641. The cubic root of 21719724 is about 279.0089281710.

The spelling of 21719724 in words is "twenty-one million, seven hundred nineteen thousand, seven hundred twenty-four".