21173500440 has 320 divisors, whose sum is σ = 76748364000. Its totient is φ = 5218007040.

The previous prime is 21173500427. The next prime is 21173500457. The reversal of 21173500440 is 4400537112.

21173500440 is a `hidden beast` number, since 2 + 1 + 173 + 50 + 0 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 79 ways as a sum of consecutive naturals, for example, 2519766 + ... + 2528154.

Almost surely, 2^21173500440 is an apocalyptic number.

21173500440 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 21173500440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38374182000).

21173500440 is an abundant number, since it is smaller than the sum of its proper divisors (55574863560).

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

21173500440 is a wasteful number, since it uses less digits than its factorization.

21173500440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8472 (or 8459 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The spelling of 21173500440 in words is "twenty-one billion, one hundred seventy-three million, five hundred thousand, four hundred forty".