21521345240 has 32 divisors (see below), whose sum is σ = 48440939760. Its totient is φ = 8605353600.

The previous prime is 21521345231. The next prime is 21521345281. The reversal of 21521345240 is 4254312512.

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, 11495 + ... + 207785.

Almost surely, 2^21521345240 is an apocalyptic number.

21521345240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21521345240 is an abundant number, since it is smaller than the sum of its proper divisors (26919594520).

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

21521345240 is a wasteful number, since it uses less digits than its factorization.

21521345240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199043 (or 199039 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 21521345240 its reverse (4254312512), we get a palindrome (25775657752).

The spelling of 21521345240 in words is "twenty-one billion, five hundred twenty-one million, three hundred forty-five thousand, two hundred forty".