21214402440 has 192 divisors, whose sum is σ = 79948874880. Its totient is φ = 4408166400.

The previous prime is 21214402439. The next prime is 21214402457. The reversal of 21214402440 is 4420441212.

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 21214402440.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2721 + ... + 206000.

It is an arithmetic number, because the mean of its divisors is an integer number (416400390).

Almost surely, 2^21214402440 is an apocalyptic number.

21214402440 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 21214402440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39974437440).

21214402440 is an abundant number, since it is smaller than the sum of its proper divisors (58734472440).

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

21214402440 is a wasteful number, since it uses less digits than its factorization.

21214402440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208764 (or 208749 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21214402440 its reverse (4420441212), we get a palindrome (25634843652).

The spelling of 21214402440 in words is "twenty-one billion, two hundred fourteen million, four hundred two thousand, four hundred forty".