21615780000 has 240 divisors, whose sum is σ = 71192411136. Its totient is φ = 5740800000.

The previous prime is 21615779981. The next prime is 21615780013. The reversal of 21615780000 is 8751612.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a self number, because there is not a number n which added to its sum of digits gives 21615780000.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 18779425 + ... + 18780575.

Almost surely, 2^21615780000 is an apocalyptic number.

21615780000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21615780000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35596205568).

21615780000 is an abundant number, since it is smaller than the sum of its proper divisors (49576631136).

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

21615780000 is a wasteful number, since it uses less digits than its factorization.

21615780000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1497 (or 1474 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 30.

The spelling of 21615780000 in words is "twenty-one billion, six hundred fifteen million, seven hundred eighty thousand".