21540302784 has 840 divisors, whose sum is σ = 87409708848. Its totient is φ = 5155799040.

The previous prime is 21540302779. The next prime is 21540302789. The reversal of 21540302784 is 48720304512.

It is a happy number.

21540302784 is a `hidden beast` number, since 2 + 1 + 540 + 30 + 2 + 7 + 84 = 666.

It is an interprime number because it is at equal distance from previous prime (21540302779) and next prime (21540302789).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540302789) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 36323992 + ... + 36324584.

Almost surely, 2^21540302784 is an apocalyptic number.

21540302784 is a gapful number since it is divisible by the number (24) 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 21540302784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43704854424).

21540302784 is an abundant number, since it is smaller than the sum of its proper divisors (65869406064).

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

21540302784 is a wasteful number, since it uses less digits than its factorization.

21540302784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 655 (or 629 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 36.

The spelling of 21540302784 in words is "twenty-one billion, five hundred forty million, three hundred two thousand, seven hundred eighty-four".