21315043 has 4 divisors (see below), whose sum is σ = 22241808. Its totient is φ = 20388280.

The previous prime is 21315037. The next prime is 21315053. The reversal of 21315043 is 34051312.

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 21315043 - 2¹⁷ = 21183971 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21315043.

It is not an unprimeable number, because it can be changed into a prime (21315013) 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, 463348 + ... + 463393.

It is an arithmetic number, because the mean of its divisors is an integer number (5560452).

Almost surely, 2^21315043 is an apocalyptic number.

21315043 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21315043 is a deficient number, since it is larger than the sum of its proper divisors (926765).

21315043 is an equidigital number, since it uses as much as digits as its factorization.

21315043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 926764.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21315043 is about 4616.8217422812. The cubic root of 21315043 is about 277.2652257725.

Adding to 21315043 its reverse (34051312), we get a palindrome (55366355).

The spelling of 21315043 in words is "twenty-one million, three hundred fifteen thousand, forty-three".