21217717752 has 96 divisors (see below), whose sum is σ = 67314136320. Its totient is φ = 5511092160.

The previous prime is 21217717739. The next prime is 21217717757. The reversal of 21217717752 is 25771771212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217717757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 807168 + ... + 833039.

It is an arithmetic number, because the mean of its divisors is an integer number (701188920).

Almost surely, 2^21217717752 is an apocalyptic number.

21217717752 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21217717752 is an abundant number, since it is smaller than the sum of its proper divisors (46096418568).

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

21217717752 is a wasteful number, since it uses less digits than its factorization.

21217717752 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1640241 (or 1640230 counting only the distinct ones).

The product of its digits is 96040, while the sum is 42.

The spelling of 21217717752 in words is "twenty-one billion, two hundred seventeen million, seven hundred seventeen thousand, seven hundred fifty-two".