21012440401 has 4 divisors (see below), whose sum is σ = 21054550000. Its totient is φ = 20970330804.

The previous prime is 21012440399. The next prime is 21012440443. The reversal of 21012440401 is 10404421012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21012440401 - 2¹ = 21012440399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010440401) 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, 21054051 + ... + 21055048.

It is an arithmetic number, because the mean of its divisors is an integer number (5263637500).

Almost surely, 2^21012440401 is an apocalyptic number.

It is an amenable number.

21012440401 is a deficient number, since it is larger than the sum of its proper divisors (42109599).

21012440401 is an equidigital number, since it uses as much as digits as its factorization.

21012440401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42109598.

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21012440401 its reverse (10404421012), we get a palindrome (31416861413).

The spelling of 21012440401 in words is "twenty-one billion, twelve million, four hundred forty thousand, four hundred one".