21402432121 has 12 divisors (see below), whose sum is σ = 25979173632. Its totient is φ = 17547334728.

The previous prime is 21402432113. The next prime is 21402432131. The reversal of 21402432121 is 12123420412.

It is not a de Polignac number, because 21402432121 - 2³ = 21402432113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21402432092 and 21402432101.

It is not an unprimeable number, because it can be changed into a prime (21402432131) 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, 9494185 + ... + 9496438.

It is an arithmetic number, because the mean of its divisors is an integer number (2164931136).

Almost surely, 2^21402432121 is an apocalyptic number.

It is an amenable number.

21402432121 is a deficient number, since it is larger than the sum of its proper divisors (4576741511).

21402432121 is a wasteful number, since it uses less digits than its factorization.

21402432121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18990660 (or 18990653 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

Adding to 21402432121 its reverse (12123420412), we get a palindrome (33525852533).

The spelling of 21402432121 in words is "twenty-one billion, four hundred two million, four hundred thirty-two thousand, one hundred twenty-one".