21665778582 has 32 divisors (see below), whose sum is σ = 49557312000. Its totient is φ = 6185780928.

The previous prime is 21665778569. The next prime is 21665778583. The reversal of 21665778582 is 28587756612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665778583) 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, 125607 + ... + 243122.

It is an arithmetic number, because the mean of its divisors is an integer number (1548666000).

Almost surely, 2^21665778582 is an apocalyptic number.

21665778582 is an abundant number, since it is smaller than the sum of its proper divisors (27891533418).

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

21665778582 is a wasteful number, since it uses less digits than its factorization.

21665778582 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370140.

The product of its digits is 11289600, while the sum is 57.

The spelling of 21665778582 in words is "twenty-one billion, six hundred sixty-five million, seven hundred seventy-eight thousand, five hundred eighty-two".