21720282 has 16 divisors (see below), whose sum is σ = 43516992. Its totient is φ = 7227360.

The previous prime is 21720277. The next prime is 21720311. The reversal of 21720282 is 28202712.

It is a happy number.

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, 918 + ... + 6654.

It is an arithmetic number, because the mean of its divisors is an integer number (2719812).

Almost surely, 2^21720282 is an apocalyptic number.

21720282 is an abundant number, since it is smaller than the sum of its proper divisors (21796710).

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

21720282 is a wasteful number, since it uses less digits than its factorization.

21720282 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6373.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21720282 is about 4660.5023334400. The cubic root of 21720282 is about 279.0113174839.

Adding to 21720282 its reverse (28202712), we get a palindrome (49922994).

The spelling of 21720282 in words is "twenty-one million, seven hundred twenty thousand, two hundred eighty-two".