21021440401 has 16 divisors (see below), whose sum is σ = 23482324096. Its totient is φ = 18693472896.

The previous prime is 21021440371. The next prime is 21021440413. The reversal of 21021440401 is 10404412012.

It is a cyclic number.

It is not a de Polignac number, because 21021440401 - 2²³ = 21013051793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021440201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 216765 + ... + 298378.

It is an arithmetic number, because the mean of its divisors is an integer number (1467645256).

Almost surely, 2^21021440401 is an apocalyptic number.

It is an amenable number.

21021440401 is a deficient number, since it is larger than the sum of its proper divisors (2460883695).

21021440401 is a wasteful number, since it uses less digits than its factorization.

21021440401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 515272.

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

Adding to 21021440401 its reverse (10404412012), we get a palindrome (31425852413).

The spelling of 21021440401 in words is "twenty-one billion, twenty-one million, four hundred forty thousand, four hundred one".