21020335440 has 160 divisors (see below), whose sum is σ = 74303744256. Its totient is φ = 4869857280.

The previous prime is 21020335439. The next prime is 21020335463. The reversal of 21020335440 is 4453302012.

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 21020335440.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 145116 + ... + 251195.

Almost surely, 2^21020335440 is an apocalyptic number.

21020335440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020335440 is an abundant number, since it is smaller than the sum of its proper divisors (53283408816).

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

21020335440 is a wasteful number, since it uses less digits than its factorization.

21020335440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396357 (or 396351 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 24.

Adding to 21020335440 its reverse (4453302012), we get a palindrome (25473637452).

The spelling of 21020335440 in words is "twenty-one billion, twenty million, three hundred thirty-five thousand, four hundred forty".