21402132421 has 4 divisors (see below), whose sum is σ = 21402452512. Its totient is φ = 21401812332.

The previous prime is 21402132397. The next prime is 21402132457. The reversal of 21402132421 is 12423120412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21402132421 - 2⁹ = 21402131909 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21402132392 and 21402132401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21402132461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17331 + ... + 207616.

It is an arithmetic number, because the mean of its divisors is an integer number (5350613128).

Almost surely, 2^21402132421 is an apocalyptic number.

It is an amenable number.

21402132421 is a deficient number, since it is larger than the sum of its proper divisors (320091).

21402132421 is an equidigital number, since it uses as much as digits as its factorization.

21402132421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320090.

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

Adding to 21402132421 its reverse (12423120412), we get a palindrome (33825252833).

The spelling of 21402132421 in words is "twenty-one billion, four hundred two million, one hundred thirty-two thousand, four hundred twenty-one".