1213779816 has 80 divisors (see below), whose sum is σ = 3406566240. Its totient is φ = 403777440.

The previous prime is 1213779811. The next prime is 1213779817. The reversal of 1213779816 is 6189773121.

It is a super-2 number, since 2×1213779816² = 2946522883457987712, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1213779811) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 378781 + ... + 381971.

It is an arithmetic number, because the mean of its divisors is an integer number (42582078).

Almost surely, 2^1213779816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1213779816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1703283120).

1213779816 is an abundant number, since it is smaller than the sum of its proper divisors (2192786424).

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

1213779816 is a wasteful number, since it uses less digits than its factorization.

1213779816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3796 (or 3783 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 1213779816 is about 34839.3429329544. The cubic root of 1213779816 is about 1066.7106647650.

The spelling of 1213779816 in words is "one billion, two hundred thirteen million, seven hundred seventy-nine thousand, eight hundred sixteen".