21401563 has 8 divisors (see below), whose sum is σ = 22343040. Its totient is φ = 20475840.

The previous prime is 21401557. The next prime is 21401593. The reversal of 21401563 is 36510412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21401563 - 2⁵ = 21401531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21401593) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1120 + ... + 6637.

It is an arithmetic number, because the mean of its divisors is an integer number (2792880).

Almost surely, 2^21401563 is an apocalyptic number.

21401563 is a deficient number, since it is larger than the sum of its proper divisors (941477).

21401563 is an equidigital number, since it uses as much as digits as its factorization.

21401563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7877.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21401563 is about 4626.1823353603. The cubic root of 21401563 is about 277.6398688886.

Adding to 21401563 its reverse (36510412), we get a palindrome (57911975).

The spelling of 21401563 in words is "twenty-one million, four hundred one thousand, five hundred sixty-three".