21264080 has 40 divisors (see below), whose sum is σ = 49783272. Its totient is φ = 8446464.

The previous prime is 21264079. The next prime is 21264101. The reversal of 21264080 is 8046212.

It can be written as a sum of positive squares in 4 ways, for example, as 506944 + 20757136 = 712^2 + 4556^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21264080² = 904322196492800, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 11714 + ... + 13406.

Almost surely, 2^21264080 is an apocalyptic number.

21264080 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 21264080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24891636).

21264080 is an abundant number, since it is smaller than the sum of its proper divisors (28519192).

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

21264080 is a wasteful number, since it uses less digits than its factorization.

21264080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1863 (or 1857 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21264080 is about 4611.2991661787. The cubic root of 21264080 is about 277.0440745378.

The spelling of 21264080 in words is "twenty-one million, two hundred sixty-four thousand, eighty".