21404204340 has 96 divisors (see below), whose sum is σ = 63291303936. Its totient is φ = 5393815680.

The previous prime is 21404204321. The next prime is 21404204359. The reversal of 21404204340 is 4340240412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21404204321) and next prime (21404204359).

It is a self number, because there is not a number n which added to its sum of digits gives 21404204340.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21105 + ... + 207975.

It is an arithmetic number, because the mean of its divisors is an integer number (659284416).

Almost surely, 2^21404204340 is an apocalyptic number.

21404204340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21404204340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31645651968).

21404204340 is an abundant number, since it is smaller than the sum of its proper divisors (41887099596).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21404204340 is a wasteful number, since it uses less digits than its factorization.

21404204340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186989 (or 186987 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 24.

Adding to 21404204340 its reverse (4340240412), we get a palindrome (25744444752).

The spelling of 21404204340 in words is "twenty-one billion, four hundred four million, two hundred four thousand, three hundred forty".