21315867 has 4 divisors (see below), whose sum is σ = 28421160. Its totient is φ = 14210576.

The previous prime is 21315823. The next prime is 21315883. The reversal of 21315867 is 76851312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21315867 - 2⁶ = 21315803 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21315067) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3552642 + ... + 3552647.

It is an arithmetic number, because the mean of its divisors is an integer number (7105290).

Almost surely, 2^21315867 is an apocalyptic number.

21315867 is a deficient number, since it is larger than the sum of its proper divisors (7105293).

21315867 is an equidigital number, since it uses as much as digits as its factorization.

21315867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7105292.

The product of its digits is 10080, while the sum is 33.

The square root of 21315867 is about 4616.9109802984. The cubic root of 21315867 is about 277.2687985794.

The spelling of 21315867 in words is "twenty-one million, three hundred fifteen thousand, eight hundred sixty-seven".