21105278740 has 48 divisors (see below), whose sum is σ = 54549032832. Its totient is φ = 6679472256.

The previous prime is 21105278729. The next prime is 21105278741. The reversal of 21105278740 is 4787250112.

It is a self number, because there is not a number n which added to its sum of digits gives 21105278740.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105278741) 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, 5796334 + ... + 5799973.

It is an arithmetic number, because the mean of its divisors is an integer number (1136438184).

Almost surely, 2^21105278740 is an apocalyptic number.

21105278740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105278740 is an abundant number, since it is smaller than the sum of its proper divisors (33443754092).

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

21105278740 is a wasteful number, since it uses less digits than its factorization.

21105278740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11596336 (or 11596334 counting only the distinct ones).

The product of its (nonzero) digits is 31360, while the sum is 37.

The spelling of 21105278740 in words is "twenty-one billion, one hundred five million, two hundred seventy-eight thousand, seven hundred forty".