1216809825 has 96 divisors (see below), whose sum is σ = 2617546752. Its totient is φ = 483648000.

The previous prime is 1216809823. The next prime is 1216809851. The reversal of 1216809825 is 5289086121.

It is a happy number.

It is not a de Polignac number, because 1216809825 - 2¹ = 1216809823 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216809823) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 128245 + ... + 137405.

It is an arithmetic number, because the mean of its divisors is an integer number (27266112).

Almost surely, 2^1216809825 is an apocalyptic number.

1216809825 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216809825 is an abundant number, since it is smaller than the sum of its proper divisors (1400736927).

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

1216809825 is a wasteful number, since it uses less digits than its factorization.

1216809825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9215 (or 9210 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 42.

The square root of 1216809825 is about 34882.8012779937. The cubic root of 1216809825 is about 1067.5975519046.

The spelling of 1216809825 in words is "one billion, two hundred sixteen million, eight hundred nine thousand, eight hundred twenty-five".