21781513032 has 64 divisors (see below), whose sum is σ = 55763484480. Its totient is φ = 7087272192.

The previous prime is 21781513027. The next prime is 21781513051. The reversal of 21781513032 is 23031518712.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21781512984 and 21781513002.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 207123 + ... + 294045.

It is an arithmetic number, because the mean of its divisors is an integer number (871304445).

Almost surely, 2^21781513032 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21781513032, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27881742240).

21781513032 is an abundant number, since it is smaller than the sum of its proper divisors (33981971448).

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

21781513032 is a wasteful number, since it uses less digits than its factorization.

21781513032 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87182 (or 87178 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 33.

The spelling of 21781513032 in words is "twenty-one billion, seven hundred eighty-one million, five hundred thirteen thousand, thirty-two".