21636480 has 128 divisors (see below), whose sum is σ = 70502400. Its totient is φ = 5642240.

The previous prime is 21636473. The next prime is 21636487. The reversal of 21636480 is 8463612.

It is an interprime number because it is at equal distance from previous prime (21636473) and next prime (21636487).

It is a tau number, because it is divible by the number of its divisors (128).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636487) 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, 113185 + ... + 113375.

It is an arithmetic number, because the mean of its divisors is an integer number (550800).

Almost surely, 2^21636480 is an apocalyptic number.

21636480 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 21636480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35251200).

21636480 is an abundant number, since it is smaller than the sum of its proper divisors (48865920).

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

21636480 is a wasteful number, since it uses less digits than its factorization.

21636480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 260 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21636480 is about 4651.5029829078. The cubic root of 21636480 is about 278.6520243929.

The spelling of 21636480 in words is "twenty-one million, six hundred thirty-six thousand, four hundred eighty".