21260720 has 40 divisors (see below), whose sum is σ = 53236176. Its totient is φ = 7849728.

The previous prime is 21260711. The next prime is 21260749. The reversal of 21260720 is 2706212.

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

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21260692 and 21260701.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9182 + ... + 11261.

Almost surely, 2^21260720 is an apocalyptic number.

21260720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21260720 is an abundant number, since it is smaller than the sum of its proper divisors (31975456).

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

21260720 is a wasteful number, since it uses less digits than its factorization.

21260720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20469 (or 20463 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21260720 is about 4610.9348292944. The cubic root of 21260720 is about 277.0294815854.

Adding to 21260720 its reverse (2706212), we get a palindrome (23966932).

The spelling of 21260720 in words is "twenty-one million, two hundred sixty thousand, seven hundred twenty".