21724354640 has 40 divisors (see below), whose sum is σ = 51874243080. Its totient is φ = 8454882816.

The previous prime is 21724354637. The next prime is 21724354699. The reversal of 21724354640 is 4645342712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7971632656 + 13752721984 = 89284^2 + 117272^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 21724354594 and 21724354603.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3666695 + ... + 3672614.

It is an arithmetic number, because the mean of its divisors is an integer number (1296856077).

Almost surely, 2^21724354640 is an apocalyptic number.

21724354640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21724354640 is an abundant number, since it is smaller than the sum of its proper divisors (30149888440).

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

21724354640 is a wasteful number, since it uses less digits than its factorization.

21724354640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7339359 (or 7339353 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 38.

The spelling of 21724354640 in words is "twenty-one billion, seven hundred twenty-four million, three hundred fifty-four thousand, six hundred forty".