21263290 has 8 divisors (see below), whose sum is σ = 38273940. Its totient is φ = 8505312.

The previous prime is 21263279. The next prime is 21263309. The reversal of 21263290 is 9236212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20985561 + 277729 = 4581^2 + 527^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1063155 + ... + 1063174.

Almost surely, 2^21263290 is an apocalyptic number.

21263290 is a deficient number, since it is larger than the sum of its proper divisors (17010650).

21263290 is a wasteful number, since it uses less digits than its factorization.

21263290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2126336.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21263290 is about 4611.2135062259. The cubic root of 21263290 is about 277.0406435950.

The spelling of 21263290 in words is "twenty-one million, two hundred sixty-three thousand, two hundred ninety".