21304402540 has 12 divisors (see below), whose sum is σ = 44739245376. Its totient is φ = 8521761008.

The previous prime is 21304402523. The next prime is 21304402547. The reversal of 21304402540 is 4520440312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21304402547) 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, 532610044 + ... + 532610083.

It is an arithmetic number, because the mean of its divisors is an integer number (3728270448).

Almost surely, 2^21304402540 is an apocalyptic number.

21304402540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21304402540 is an abundant number, since it is smaller than the sum of its proper divisors (23434842836).

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

21304402540 is a wasteful number, since it uses less digits than its factorization.

21304402540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065220136 (or 1065220134 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 25.

Adding to 21304402540 its reverse (4520440312), we get a palindrome (25824842852).

The spelling of 21304402540 in words is "twenty-one billion, three hundred four million, four hundred two thousand, five hundred forty".