1331561216 has 72 divisors (see below), whose sum is σ = 2791654320. Its totient is φ = 632991744.

The previous prime is 1331561213. The next prime is 1331561219. The reversal of 1331561216 is 6121651331.

It is an interprime number because it is at equal distance from previous prime (1331561213) and next prime (1331561219).

It is a Harshad number since it is a multiple of its sum of digits (29).

It is not an unprimeable number, because it can be changed into a prime (1331561213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 496070 + ... + 498746.

Almost surely, 2^1331561216 is an apocalyptic number.

1331561216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1331561216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1395827160).

1331561216 is an abundant number, since it is smaller than the sum of its proper divisors (1460093104).

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

1331561216 is an equidigital number, since it uses as much as digits as its factorization.

1331561216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2789 (or 2775 counting only the distinct ones).

The product of its digits is 3240, while the sum is 29.

The square root of 1331561216 is about 36490.5633828802. The cubic root of 1331561216 is about 1100.1545832340.

The spelling of 1331561216 in words is "one billion, three hundred thirty-one million, five hundred sixty-one thousand, two hundred sixteen".