21366781830 has 80 divisors (see below), whose sum is σ = 59005766160. Its totient is φ = 5543805888.

The previous prime is 21366781817. The next prime is 21366781897. The reversal of 21366781830 is 3818766312.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 326500 + ... + 386439.

It is an arithmetic number, because the mean of its divisors is an integer number (737572077).

Almost surely, 2^21366781830 is an apocalyptic number.

21366781830 is an abundant number, since it is smaller than the sum of its proper divisors (37638984330).

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

21366781830 is a wasteful number, since it uses less digits than its factorization.

21366781830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712995 (or 712986 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The spelling of 21366781830 in words is "twenty-one billion, three hundred sixty-six million, seven hundred eighty-one thousand, eight hundred thirty".