21087427440 has 80 divisors (see below), whose sum is σ = 65568767616. Its totient is φ = 5606304000.

The previous prime is 21087427397. The next prime is 21087427447. The reversal of 21087427440 is 4472478012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21087427447) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 53286 + ... + 212165.

Almost surely, 2^21087427440 is an apocalyptic number.

21087427440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21087427440 is an abundant number, since it is smaller than the sum of its proper divisors (44481340176).

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

21087427440 is a wasteful number, since it uses less digits than its factorization.

21087427440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265798 (or 265792 counting only the distinct ones).

The product of its (nonzero) digits is 100352, while the sum is 39.

The spelling of 21087427440 in words is "twenty-one billion, eighty-seven million, four hundred twenty-seven thousand, four hundred forty".