1215306820 has 72 divisors (see below), whose sum is σ = 3197225304. Its totient is φ = 384620544.

The previous prime is 1215306811. The next prime is 1215306877. The reversal of 1215306820 is 286035121.

It can be written as a sum of positive squares in 4 ways, for example, as 224820036 + 990486784 = 14994^2 + 31472^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34957 + ... + 60436.

It is an arithmetic number, because the mean of its divisors is an integer number (44405907).

Almost surely, 2^1215306820 is an apocalyptic number.

1215306820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1215306820 is an abundant number, since it is smaller than the sum of its proper divisors (1981918484).

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

1215306820 is a wasteful number, since it uses less digits than its factorization.

1215306820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95429 (or 95420 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 1215306820 is about 34861.2509815698. The cubic root of 1215306820 is about 1067.1578048576.

The spelling of 1215306820 in words is "one billion, two hundred fifteen million, three hundred six thousand, eight hundred twenty".