21035501440 has 128 divisors (see below), whose sum is σ = 51045059520. Its totient is φ = 8288501760.

The previous prime is 21035501323. The next prime is 21035501441. The reversal of 21035501440 is 4410553012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21035501441) 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, 13089117 + ... + 13090723.

Almost surely, 2^21035501440 is an apocalyptic number.

21035501440 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 21035501440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25522529760).

21035501440 is an abundant number, since it is smaller than the sum of its proper divisors (30009558080).

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

21035501440 is a wasteful number, since it uses less digits than its factorization.

21035501440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1920 (or 1908 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

The spelling of 21035501440 in words is "twenty-one billion, thirty-five million, five hundred one thousand, four hundred forty".