21243780988 has 12 divisors (see below), whose sum is σ = 38458569240. Its totient is φ = 10255618352.

The previous prime is 21243780983. The next prime is 21243780997. The reversal of 21243780988 is 88908734212.

It is a happy number.

It is a super-2 number, since 2×21243780988² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243780983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91567906 + ... + 91568137.

It is an arithmetic number, because the mean of its divisors is an integer number (3204880770).

Almost surely, 2^21243780988 is an apocalyptic number.

It is an amenable number.

21243780988 is a deficient number, since it is larger than the sum of its proper divisors (17214788252).

21243780988 is a wasteful number, since it uses less digits than its factorization.

21243780988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183136076 (or 183136074 counting only the distinct ones).

The product of its (nonzero) digits is 1548288, while the sum is 52.

The spelling of 21243780988 in words is "twenty-one billion, two hundred forty-three million, seven hundred eighty thousand, nine hundred eighty-eight".