1216156580 has 24 divisors (see below), whose sum is σ = 2555464128. Its totient is φ = 486170208.

The previous prime is 1216156577. The next prime is 1216156583. The reversal of 1216156580 is 856516121.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1216156577) and next prime (1216156583).

It is a self number, because there is not a number n which added to its sum of digits gives 1216156580.

It is not an unprimeable number, because it can be changed into a prime (1216156583) 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, 17537 + ... + 52343.

It is an arithmetic number, because the mean of its divisors is an integer number (106477672).

Almost surely, 2^1216156580 is an apocalyptic number.

1216156580 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1216156580 is an abundant number, since it is smaller than the sum of its proper divisors (1339307548).

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

1216156580 is a wasteful number, since it uses less digits than its factorization.

1216156580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36563 (or 36561 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 35.

The square root of 1216156580 is about 34873.4365957816. The cubic root of 1216156580 is about 1067.4064709359.

The spelling of 1216156580 in words is "one billion, two hundred sixteen million, one hundred fifty-six thousand, five hundred eighty".