21240021401 has 16 divisors (see below), whose sum is σ = 21752893440. Its totient is φ = 20733773760.

The previous prime is 21240021379. The next prime is 21240021427. The reversal of 21240021401 is 10412004212.

It is a cyclic number.

It is not a de Polignac number, because 21240021401 - 2¹⁰ = 21240020377 is a prime.

It is a super-2 number, since 2×21240021401² (a number of 21 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 21240021401.

It is not an unprimeable number, because it can be changed into a prime (21240021001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5020355 + ... + 5024583.

It is an arithmetic number, because the mean of its divisors is an integer number (1359555840).

Almost surely, 2^21240021401 is an apocalyptic number.

It is an amenable number.

21240021401 is a deficient number, since it is larger than the sum of its proper divisors (512872039).

21240021401 is a wasteful number, since it uses less digits than its factorization.

21240021401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4984.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21240021401 its reverse (10412004212), we get a palindrome (31652025613).

The spelling of 21240021401 in words is "twenty-one billion, two hundred forty million, twenty-one thousand, four hundred one".