21401115565 has 8 divisors (see below), whose sum is σ = 25774052760. Its totient is φ = 17059083072.

The previous prime is 21401115559. The next prime is 21401115581. The reversal of 21401115565 is 56551110412.

It can be written as a sum of positive squares in 4 ways, for example, as 428572804 + 20972542761 = 20702^2 + 144819^2 .

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 21401115565 - 2²⁵ = 21367561133 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7724650 + ... + 7727419.

It is an arithmetic number, because the mean of its divisors is an integer number (3221756595).

Almost surely, 2^21401115565 is an apocalyptic number.

It is an amenable number.

21401115565 is a deficient number, since it is larger than the sum of its proper divisors (4372937195).

21401115565 is a wasteful number, since it uses less digits than its factorization.

21401115565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15452351.

The product of its (nonzero) digits is 6000, while the sum is 31.

Adding to 21401115565 its reverse (56551110412), we get a palindrome (77952225977).

The spelling of 21401115565 in words is "twenty-one billion, four hundred one million, one hundred fifteen thousand, five hundred sixty-five".