21219637440 has 112 divisors (see below), whose sum is σ = 67453934688. Its totient is φ = 5651718144.

The previous prime is 21219637421. The next prime is 21219637447. The reversal of 21219637440 is 4473691212.

It is not an unprimeable number, because it can be changed into a prime (21219637447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 805924 + ... + 831836.

It is an arithmetic number, because the mean of its divisors is an integer number (602267274).

Almost surely, 2^21219637440 is an apocalyptic number.

21219637440 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 21219637440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33726967344).

21219637440 is an abundant number, since it is smaller than the sum of its proper divisors (46234297248).

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

21219637440 is a wasteful number, since it uses less digits than its factorization.

21219637440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26786 (or 26776 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 39.

The spelling of 21219637440 in words is "twenty-one billion, two hundred nineteen million, six hundred thirty-seven thousand, four hundred forty".