21401423421 has 16 divisors (see below), whose sum is σ = 32916478464. Its totient is φ = 12115090224.

The previous prime is 21401423419. The next prime is 21401423447. The reversal of 21401423421 is 12432410412.

It is not a de Polignac number, because 21401423421 - 2¹ = 21401423419 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21401423391 and 21401423400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401423401) 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, 4759975 + ... + 4764468.

It is an arithmetic number, because the mean of its divisors is an integer number (2057279904).

Almost surely, 2^21401423421 is an apocalyptic number.

21401423421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21401423421 is a deficient number, since it is larger than the sum of its proper divisors (11515055043).

21401423421 is a wasteful number, since it uses less digits than its factorization.

21401423421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9524560.

The product of its (nonzero) digits is 1536, while the sum is 24.

Adding to 21401423421 its reverse (12432410412), we get a palindrome (33833833833).

The spelling of 21401423421 in words is "twenty-one billion, four hundred one million, four hundred twenty-three thousand, four hundred twenty-one".