21201321434401 has 4 divisors (see below), whose sum is σ = 21201395388804. Its totient is φ = 21201247480000.

The previous prime is 21201321434353. The next prime is 21201321434413. The reversal of 21201321434401 is 10443412310212.

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 11043332568801 + 10157988865600 = 3323151^2 + 3187160^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201321434401 - 2¹⁹ = 21201320910113 is a prime.

It is a super-2 number, since 2×21201321434401² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201321434401.

It is not an unprimeable number, because it can be changed into a prime (21201321435401) 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, 36545500 + ... + 37121101.

It is an arithmetic number, because the mean of its divisors is an integer number (5300348847201).

Almost surely, 2^{21201321434401} is an apocalyptic number.

It is an amenable number.

21201321434401 is a deficient number, since it is larger than the sum of its proper divisors (73954403).

21201321434401 is an equidigital number, since it uses as much as digits as its factorization.

21201321434401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73954402.

The product of its (nonzero) digits is 4608, while the sum is 28.

Adding to 21201321434401 its reverse (10443412310212), we get a palindrome (31644733744613).

The spelling of 21201321434401 in words is "twenty-one trillion, two hundred one billion, three hundred twenty-one million, four hundred thirty-four thousand, four hundred one".