21178287212 has 24 divisors (see below), whose sum is σ = 37619089200. Its totient is φ = 10431041600.

The previous prime is 21178287203. The next prime is 21178287269. The reversal of 21178287212 is 21278287112.

It is a self number, because there is not a number n which added to its sum of digits gives 21178287212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53462 + ... + 212637.

It is an arithmetic number, because the mean of its divisors is an integer number (1567462050).

Almost surely, 2^21178287212 is an apocalyptic number.

It is an amenable number.

21178287212 is a deficient number, since it is larger than the sum of its proper divisors (16440801988).

21178287212 is a wasteful number, since it uses less digits than its factorization.

21178287212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266401 (or 266399 counting only the distinct ones).

The product of its digits is 50176, while the sum is 41.

The spelling of 21178287212 in words is "twenty-one billion, one hundred seventy-eight million, two hundred eighty-seven thousand, two hundred twelve".