1216753978 has 12 divisors (see below), whose sum is σ = 2006136090. Its totient is φ = 553069880.

The previous prime is 1216753961. The next prime is 1216753997. The reversal of 1216753978 is 8793576121.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 758066089 + 458687889 = 27533^2 + 21417^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2513713 + ... + 2514196.

Almost surely, 2^1216753978 is an apocalyptic number.

1216753978 is a deficient number, since it is larger than the sum of its proper divisors (789382112).

1216753978 is a wasteful number, since it uses less digits than its factorization.

1216753978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027933 (or 5027922 counting only the distinct ones).

The product of its digits is 635040, while the sum is 49.

The square root of 1216753978 is about 34882.0007740382. Note that the first 3 decimals coincide. The cubic root of 1216753978 is about 1067.5812187490.

The spelling of 1216753978 in words is "one billion, two hundred sixteen million, seven hundred fifty-three thousand, nine hundred seventy-eight".