1216521712 has 20 divisors (see below), whose sum is σ = 2693726896. Its totient is φ = 521366400.

The previous prime is 1216521673. The next prime is 1216521737. The reversal of 1216521712 is 2171256121.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5430789 + ... + 5431012.

Almost surely, 2^1216521712 is an apocalyptic number.

It is an amenable number.

1216521712 is an abundant number, since it is smaller than the sum of its proper divisors (1477205184).

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

1216521712 is a wasteful number, since it uses less digits than its factorization.

1216521712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10861816 (or 10861810 counting only the distinct ones).

The product of its digits is 1680, while the sum is 28.

The square root of 1216521712 is about 34878.6713049680. The cubic root of 1216521712 is about 1067.5132842820.

Adding to 1216521712 its reverse (2171256121), we get a palindrome (3387777833).

The spelling of 1216521712 in words is "one billion, two hundred sixteen million, five hundred twenty-one thousand, seven hundred twelve".