21821315 has 8 divisors (see below), whose sum is σ = 26271648. Its totient is φ = 17399680.

The previous prime is 21821309. The next prime is 21821321. The reversal of 21821315 is 51312812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21821309) and next prime (21821321).

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

It is not a de Polignac number, because 21821315 - 2¹² = 21817219 is a prime.

It is a Duffinian 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, 5462 + ... + 8571.

It is an arithmetic number, because the mean of its divisors is an integer number (3283956).

Almost surely, 2^21821315 is an apocalyptic number.

21821315 is a deficient number, since it is larger than the sum of its proper divisors (4450333).

21821315 is a wasteful number, since it uses less digits than its factorization.

21821315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14349.

The product of its digits is 480, while the sum is 23.

The square root of 21821315 is about 4671.3290400056. The cubic root of 21821315 is about 279.4432602333.

The spelling of 21821315 in words is "twenty-one million, eight hundred twenty-one thousand, three hundred fifteen".