21502542134201 has 4 divisors (see below), whose sum is σ = 21508302261732. Its totient is φ = 21496782006672.

The previous prime is 21502542134197. The next prime is 21502542134267. The reversal of 21502542134201 is 10243124520512.

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 15769031608576 + 5733510525625 = 3971024^2 + 2394475^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502542134201 - 2² = 21502542134197 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21502542134401) 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, 2880058166 + ... + 2880065631.

It is an arithmetic number, because the mean of its divisors is an integer number (5377075565433).

Almost surely, 2^{21502542134201} is an apocalyptic number.

It is an amenable number.

21502542134201 is a deficient number, since it is larger than the sum of its proper divisors (5760127531).

21502542134201 is an equidigital number, since it uses as much as digits as its factorization.

21502542134201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5760127530.

The product of its (nonzero) digits is 19200, while the sum is 32.

Adding to 21502542134201 its reverse (10243124520512), we get a palindrome (31745666654713).

The spelling of 21502542134201 in words is "twenty-one trillion, five hundred two billion, five hundred forty-two million, one hundred thirty-four thousand, two hundred one".