21036505780 has 48 divisors (see below), whose sum is σ = 44400726720. Its totient is φ = 8372000000.

The previous prime is 21036505753. The next prime is 21036505781. The reversal of 21036505780 is 8750563012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036505781) 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, 6469155 + ... + 6472405.

It is an arithmetic number, because the mean of its divisors is an integer number (925015140).

Almost surely, 2^21036505780 is an apocalyptic number.

21036505780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21036505780 is an abundant number, since it is smaller than the sum of its proper divisors (23364220940).

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

21036505780 is a wasteful number, since it uses less digits than its factorization.

21036505780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4800 (or 4798 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21036505780 in words is "twenty-one billion, thirty-six million, five hundred five thousand, seven hundred eighty".