21081963 has 16 divisors (see below), whose sum is σ = 33816320. Its totient is φ = 11412576.

The previous prime is 21081947. The next prime is 21081979. The reversal of 21081963 is 36918012.

It is an interprime number because it is at equal distance from previous prime (21081947) and next prime (21081979).

It is not a de Polignac number, because 21081963 - 2⁴ = 21081947 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 21081963.

It is not an unprimeable number, because it can be changed into a prime (21081923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26020 + ... + 26817.

It is an arithmetic number, because the mean of its divisors is an integer number (2113520).

Almost surely, 2^21081963 is an apocalyptic number.

21081963 is a deficient number, since it is larger than the sum of its proper divisors (12734357).

21081963 is a wasteful number, since it uses less digits than its factorization.

21081963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52866.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21081963 is about 4591.5098823807. The cubic root of 21081963 is about 276.2508877076.

Adding to 21081963 its reverse (36918012), we get a palindrome (57999975).

The spelling of 21081963 in words is "twenty-one million, eighty-one thousand, nine hundred sixty-three".