21724154240 has 64 divisors (see below), whose sum is σ = 52163440560. Its totient is φ = 8651323392.

The previous prime is 21724154237. The next prime is 21724154273. The reversal of 21724154240 is 4245142712.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21724154197 and 21724154206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70514 + ... + 220046.

Almost surely, 2^21724154240 is an apocalyptic number.

21724154240 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 21724154240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26081720280).

21724154240 is an abundant number, since it is smaller than the sum of its proper divisors (30439286320).

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

21724154240 is a wasteful number, since it uses less digits than its factorization.

21724154240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149779 (or 149767 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 32.

Adding to 21724154240 its reverse (4245142712), we get a palindrome (25969296952).

The spelling of 21724154240 in words is "twenty-one billion, seven hundred twenty-four million, one hundred fifty-four thousand, two hundred forty".