1251220120 has 64 divisors (see below), whose sum is σ = 2897971200. Its totient is φ = 485844480.

The previous prime is 1251220099. The next prime is 1251220121. The reversal of 1251220120 is 210221521.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1251220094 and 1251220103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251220121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 977641 + ... + 978919.

It is an arithmetic number, because the mean of its divisors is an integer number (45280800).

Almost surely, 2^1251220120 is an apocalyptic number.

1251220120 is a gapful number since it is divisible by the number (10) 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 1251220120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1448985600).

1251220120 is an abundant number, since it is smaller than the sum of its proper divisors (1646751080).

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

1251220120 is a wasteful number, since it uses less digits than its factorization.

1251220120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1988 (or 1984 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 1251220120 is about 35372.5899532392. The cubic root of 1251220120 is about 1077.5677202212.

Adding to 1251220120 its reverse (210221521), we get a palindrome (1461441641).

The spelling of 1251220120 in words is "one billion, two hundred fifty-one million, two hundred twenty thousand, one hundred twenty".