21289367520 has 144 divisors (see below), whose sum is σ = 72971130960. Its totient is φ = 5652068352.

The previous prime is 21289367419. The next prime is 21289367531. The reversal of 21289367520 is 2576398212.

21289367520 is a `hidden beast` number, since 2 + 1 + 289 + 367 + 5 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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 23 ways as a sum of consecutive naturals, for example, 294316 + ... + 359444.

It is an arithmetic number, because the mean of its divisors is an integer number (506743965).

Almost surely, 2^21289367520 is an apocalyptic number.

21289367520 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 21289367520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36485565480).

21289367520 is an abundant number, since it is smaller than the sum of its proper divisors (51681763440).

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

21289367520 is a wasteful number, since it uses less digits than its factorization.

21289367520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65377 (or 65366 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 21289367520 in words is "twenty-one billion, two hundred eighty-nine million, three hundred sixty-seven thousand, five hundred twenty".