21518409700 has 18 divisors (see below), whose sum is σ = 46694949266. Its totient is φ = 8607363840.

The previous prime is 21518409691. The next prime is 21518409763. The reversal of 21518409700 is 790481512.

It can be written as a sum of positive squares in 3 ways, for example, as 660695616 + 20857714084 = 25704^2 + 144422^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21518409700.

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 5 ways as a sum of consecutive naturals, for example, 107591949 + ... + 107592148.

Almost surely, 2^21518409700 is an apocalyptic number.

21518409700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21518409700 is an abundant number, since it is smaller than the sum of its proper divisors (25176539566).

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

21518409700 is a wasteful number, since it uses less digits than its factorization.

21518409700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215184111 (or 215184104 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 37.

The spelling of 21518409700 in words is "twenty-one billion, five hundred eighteen million, four hundred nine thousand, seven hundred".