21316542 has 16 divisors (see below), whose sum is σ = 45912720. Its totient is φ = 6558912.

The previous prime is 21316531. The next prime is 21316553. The reversal of 21316542 is 24561312.

It is an interprime number because it is at equal distance from previous prime (21316531) and next prime (21316553).

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 136567 + ... + 136722.

It is an arithmetic number, because the mean of its divisors is an integer number (2869545).

Almost surely, 2^21316542 is an apocalyptic number.

21316542 is an abundant number, since it is smaller than the sum of its proper divisors (24596178).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21316542 is a wasteful number, since it uses less digits than its factorization.

21316542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273307.

The product of its digits is 1440, while the sum is 24.

The square root of 21316542 is about 4616.9840805444. The cubic root of 21316542 is about 277.2717252641.

Adding to 21316542 its reverse (24561312), we get a palindrome (45877854).

The spelling of 21316542 in words is "twenty-one million, three hundred sixteen thousand, five hundred forty-two".