21280815072 has 240 divisors, whose sum is σ = 68602609152. Its totient is φ = 6417895680.

The previous prime is 21280815047. The next prime is 21280815091. The reversal of 21280815072 is 27051808212.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 6356503 + ... + 6359849.

Almost surely, 2^21280815072 is an apocalyptic number.

21280815072 is a gapful number since it is divisible by the number (22) 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 21280815072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34301304576).

21280815072 is an abundant number, since it is smaller than the sum of its proper divisors (47321794080).

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

21280815072 is a wasteful number, since it uses less digits than its factorization.

21280815072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3603 (or 3586 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The spelling of 21280815072 in words is "twenty-one billion, two hundred eighty million, eight hundred fifteen thousand, seventy-two".