21255354163601 has 4 divisors (see below), whose sum is σ = 21272372062500. Its totient is φ = 21238336264704.

The previous prime is 21255354163559. The next prime is 21255354163619. The reversal of 21255354163601 is 10636145355212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5564050662976 + 15691303500625 = 2358824^2 + 3961225^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21255354163601 is a prime.

It is a super-2 number, since 2×21255354163601² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255354163501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8508947576 + ... + 8508950073.

It is an arithmetic number, because the mean of its divisors is an integer number (5318093015625).

Almost surely, 2^{21255354163601} is an apocalyptic number.

It is an amenable number.

21255354163601 is a deficient number, since it is larger than the sum of its proper divisors (17017898899).

21255354163601 is a wasteful number, since it uses less digits than its factorization.

21255354163601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17017898898.

The product of its (nonzero) digits is 648000, while the sum is 44.

The spelling of 21255354163601 in words is "twenty-one trillion, two hundred fifty-five billion, three hundred fifty-four million, one hundred sixty-three thousand, six hundred one".