21121404421 has 16 divisors (see below), whose sum is σ = 23048432064. Its totient is φ = 19238989824.

The previous prime is 21121404419. The next prime is 21121404431. The reversal of 21121404421 is 12440412112.

It is a cyclic number.

It is not a de Polignac number, because 21121404421 - 2¹ = 21121404419 is a prime.

It is a super-2 number, since 2×21121404421² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121404392 and 21121404401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121404431) 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, 327946 + ... + 387028.

It is an arithmetic number, because the mean of its divisors is an integer number (1440527004).

Almost surely, 2^21121404421 is an apocalyptic number.

It is an amenable number.

21121404421 is a deficient number, since it is larger than the sum of its proper divisors (1927027643).

21121404421 is a wasteful number, since it uses less digits than its factorization.

21121404421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59460.

The product of its (nonzero) digits is 512, while the sum is 22.

Adding to 21121404421 its reverse (12440412112), we get a palindrome (33561816533).

The spelling of 21121404421 in words is "twenty-one billion, one hundred twenty-one million, four hundred four thousand, four hundred twenty-one".