1251121320 has 96 divisors (see below), whose sum is σ = 4071249000. Its totient is φ = 333213696.

The previous prime is 1251121279. The next prime is 1251121321. The reversal of 1251121320 is 231211521.

It can be written as a sum of positive squares in 4 ways, for example, as 1250188164 + 933156 = 35358^2 + 966^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 1251121293 and 1251121302.

It is not an unprimeable number, because it can be changed into a prime (1251121321) 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, 375984 + ... + 379296.

Almost surely, 2^1251121320 is an apocalyptic number.

1251121320 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 1251121320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2035624500).

1251121320 is an abundant number, since it is smaller than the sum of its proper divisors (2820127680).

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

1251121320 is a wasteful number, since it uses less digits than its factorization.

1251121320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4379 (or 4372 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 1251121320 is about 35371.1933640922. The cubic root of 1251121320 is about 1077.5393568418.

Adding to 1251121320 its reverse (231211521), we get a palindrome (1482332841).

The spelling of 1251121320 in words is "one billion, two hundred fifty-one million, one hundred twenty-one thousand, three hundred twenty".