21718528240 has 40 divisors (see below), whose sum is σ = 50777709840. Its totient is φ = 8638872576.

The previous prime is 21718528231. The next prime is 21718528253. The reversal of 21718528240 is 4282581712.

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

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 21718528193 and 21718528202.

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, 744009 + ... + 772648.

It is an arithmetic number, because the mean of its divisors is an integer number (1269442746).

Almost surely, 2^21718528240 is an apocalyptic number.

21718528240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21718528240 is an abundant number, since it is smaller than the sum of its proper divisors (29059181600).

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

21718528240 is a wasteful number, since it uses less digits than its factorization.

21718528240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1516849 (or 1516843 counting only the distinct ones).

The product of its (nonzero) digits is 71680, while the sum is 40.

The spelling of 21718528240 in words is "twenty-one billion, seven hundred eighteen million, five hundred twenty-eight thousand, two hundred forty".