21400423440 has 320 divisors, whose sum is σ = 75423744000. Its totient is φ = 4972492800.

The previous prime is 21400423423. The next prime is 21400423453. The reversal of 21400423440 is 4432400412.

It is a happy number.

It is a super-2 number, since 2×21400423440² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21400423440.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8919361 + ... + 8921759.

It is an arithmetic number, because the mean of its divisors is an integer number (235699200).

Almost surely, 2^21400423440 is an apocalyptic number.

21400423440 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 21400423440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37711872000).

21400423440 is an abundant number, since it is smaller than the sum of its proper divisors (54023320560).

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

21400423440 is a wasteful number, since it uses less digits than its factorization.

21400423440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2566 (or 2560 counting only the distinct ones).

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

Adding to 21400423440 its reverse (4432400412), we get a palindrome (25832823852).

The spelling of 21400423440 in words is "twenty-one billion, four hundred million, four hundred twenty-three thousand, four hundred forty".