21240512120 has 32 divisors (see below), whose sum is σ = 48601177200. Its totient is φ = 8352200448.

The previous prime is 21240512119. The next prime is 21240512149. The reversal of 21240512120 is 2121504212.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21240512092 and 21240512101.

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 7 ways as a sum of consecutive naturals, for example, 4497749 + ... + 4502468.

Almost surely, 2^21240512120 is an apocalyptic number.

21240512120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240512120 is an abundant number, since it is smaller than the sum of its proper divisors (27360665080).

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

21240512120 is a wasteful number, since it uses less digits than its factorization.

21240512120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9000287 (or 9000283 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The spelling of 21240512120 in words is "twenty-one billion, two hundred forty million, five hundred twelve thousand, one hundred twenty".