21204011421 has 12 divisors (see below), whose sum is σ = 30675806460. Its totient is φ = 14113950720.

The previous prime is 21204011347. The next prime is 21204011429. The reversal of 21204011421 is 12411040212.

21204011421 is a `hidden beast` number, since 2 + 120 + 401 + 142 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 17613005796 + 3591005625 = 132714^2 + 59925^2 .

It is not a de Polignac number, because 21204011421 - 2⁹ = 21204010909 is a prime.

It is a super-2 number, since 2×21204011421² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21204011394 and 21204011403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204011429) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1831986 + ... + 1843523.

It is an arithmetic number, because the mean of its divisors is an integer number (2556317205).

Almost surely, 2^21204011421 is an apocalyptic number.

It is an amenable number.

21204011421 is a deficient number, since it is larger than the sum of its proper divisors (9471795039).

21204011421 is a wasteful number, since it uses less digits than its factorization.

21204011421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3676156 (or 3676153 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21204011421 its reverse (12411040212), we get a palindrome (33615051633).

The spelling of 21204011421 in words is "twenty-one billion, two hundred four million, eleven thousand, four hundred twenty-one".