21391286 has 8 divisors (see below), whose sum is σ = 36670800. Its totient is φ = 9167688.

The previous prime is 21391267. The next prime is 21391301. The reversal of 21391286 is 68219312.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 763961 + ... + 763988.

It is an arithmetic number, because the mean of its divisors is an integer number (4583850).

Almost surely, 2^21391286 is an apocalyptic number.

21391286 is a deficient number, since it is larger than the sum of its proper divisors (15279514).

21391286 is a wasteful number, since it uses less digits than its factorization.

21391286 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1527958.

The product of its digits is 5184, while the sum is 32.

The square root of 21391286 is about 4625.0714589074. The cubic root of 21391286 is about 277.5954210170.

The spelling of 21391286 in words is "twenty-one million, three hundred ninety-one thousand, two hundred eighty-six".