21286790 has 32 divisors (see below), whose sum is σ = 44864064. Its totient is φ = 7119360.

The previous prime is 21286789. The next prime is 21286813. The reversal of 21286790 is 9768212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21286790.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 839 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (1402002).

Almost surely, 2^21286790 is an apocalyptic number.

21286790 is an abundant number, since it is smaller than the sum of its proper divisors (23577274).

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

21286790 is a wasteful number, since it uses less digits than its factorization.

21286790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7472.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 21286790 is about 4613.7609387570. The cubic root of 21286790 is about 277.1426669753.

The spelling of 21286790 in words is "twenty-one million, two hundred eighty-six thousand, seven hundred ninety".