21440295440 has 40 divisors (see below), whose sum is σ = 49856582040. Its totient is φ = 8574759936.

The previous prime is 21440295431. The next prime is 21440295449. The reversal of 21440295440 is 4459204412.

It is an interprime number because it is at equal distance from previous prime (21440295431) and next prime (21440295449).

It can be written as a sum of positive squares in 4 ways, for example, as 2650384 + 21437645056 = 1628^2 + 146416^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 21440295440.

It is not an unprimeable number, because it can be changed into a prime (21440295449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 599996 + ... + 634724.

It is an arithmetic number, because the mean of its divisors is an integer number (1246414551).

Almost surely, 2^21440295440 is an apocalyptic number.

21440295440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21440295440 is an abundant number, since it is smaller than the sum of its proper divisors (28416286600).

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

21440295440 is a wasteful number, since it uses less digits than its factorization.

21440295440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42459 (or 42453 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 35.

Adding to 21440295440 its reverse (4459204412), we get a palindrome (25899499852).

The spelling of 21440295440 in words is "twenty-one billion, four hundred forty million, two hundred ninety-five thousand, four hundred forty".