21280790 has 16 divisors (see below), whose sum is σ = 38737440. Its totient is φ = 8416320.

The previous prime is 21280789. The next prime is 21280793. The reversal of 21280790 is 9708212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280793) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11066 + ... + 12845.

It is an arithmetic number, because the mean of its divisors is an integer number (2421090).

Almost surely, 2^21280790 is an apocalyptic number.

21280790 is a deficient number, since it is larger than the sum of its proper divisors (17456650).

21280790 is a wasteful number, since it uses less digits than its factorization.

21280790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24007.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21280790 is about 4613.1106641831. The cubic root of 21280790 is about 277.1166255937.

The spelling of 21280790 in words is "twenty-one million, two hundred eighty thousand, seven hundred ninety".