21016361 has 4 divisors (see below), whose sum is σ = 21052752. Its totient is φ = 20979972.

The previous prime is 21016309. The next prime is 21016381. The reversal of 21016361 is 16361012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21016361 - 2⁶ = 21016297 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21016381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17315 + ... + 18488.

It is an arithmetic number, because the mean of its divisors is an integer number (5263188).

Almost surely, 2^21016361 is an apocalyptic number.

It is an amenable number.

21016361 is a deficient number, since it is larger than the sum of its proper divisors (36391).

21016361 is an equidigital number, since it uses as much as digits as its factorization.

21016361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36390.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21016361 is about 4584.3604788454. The cubic root of 21016361 is about 275.9640478620.

Adding to 21016361 its reverse (16361012), we get a palindrome (37377373).

The spelling of 21016361 in words is "twenty-one million, sixteen thousand, three hundred sixty-one".