21354404240 has 80 divisors (see below), whose sum is σ = 53643108288. Its totient is φ = 7858902528.

The previous prime is 21354404233. The next prime is 21354404249. The reversal of 21354404240 is 4240445312.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (21354404249) 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, 285839 + ... + 352721.

Almost surely, 2^21354404240 is an apocalyptic number.

21354404240 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 21354404240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26821554144).

21354404240 is an abundant number, since it is smaller than the sum of its proper divisors (32288704048).

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

21354404240 is a wasteful number, since it uses less digits than its factorization.

21354404240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67216 (or 67210 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 29.

Adding to 21354404240 its reverse (4240445312), we get a palindrome (25594849552).

The spelling of 21354404240 in words is "twenty-one billion, three hundred fifty-four million, four hundred four thousand, two hundred forty".