1217087820 has 72 divisors (see below), whose sum is σ = 3975827856. Its totient is φ = 299590272.

The previous prime is 1217087819. The next prime is 1217087821. The reversal of 1217087820 is 287807121.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1217087819) and next prime (1217087821).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (1217087821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 257722 + ... + 262401.

Almost surely, 2^1217087820 is an apocalyptic number.

1217087820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1217087820 is an abundant number, since it is smaller than the sum of its proper divisors (2758740036).

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

1217087820 is a wasteful number, since it uses less digits than its factorization.

1217087820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520151 (or 520146 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The square root of 1217087820 is about 34886.7857504815. The cubic root of 1217087820 is about 1067.6788475946.

The spelling of 1217087820 in words is "one billion, two hundred seventeen million, eighty-seven thousand, eight hundred twenty".