21506263013101 has 4 divisors (see below), whose sum is σ = 21912041560572. Its totient is φ = 21100484465632.

The previous prime is 21506263013069. The next prime is 21506263013107. The reversal of 21506263013101 is 10131036260512.

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 19347637974025 + 2158625039076 = 4398595^2 + 1469226^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506263013101 - 2⁵ = 21506263013069 is a prime.

It is a super-2 number, since 2×21506263013101² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506263013107) 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, 202889273656 + ... + 202889273761.

It is an arithmetic number, because the mean of its divisors is an integer number (5478010390143).

Almost surely, 2^{21506263013101} is an apocalyptic number.

It is an amenable number.

21506263013101 is a deficient number, since it is larger than the sum of its proper divisors (405778547471).

21506263013101 is an equidigital number, since it uses as much as digits as its factorization.

21506263013101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405778547470.

The product of its (nonzero) digits is 6480, while the sum is 31.

Adding to 21506263013101 its reverse (10131036260512), we get a palindrome (31637299273613).

The spelling of 21506263013101 in words is "twenty-one trillion, five hundred six billion, two hundred sixty-three million, thirteen thousand, one hundred one".