1251605440 has 112 divisors (see below), whose sum is σ = 3051718560. Its totient is φ = 488816640.

The previous prime is 1251605437. The next prime is 1251605489. The reversal of 1251605440 is 445061521.

It is a junction number, because it is equal to n+sod(n) for n = 1251605399 and 1251605408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3059956 + ... + 3060364.

Almost surely, 2^1251605440 is an apocalyptic number.

1251605440 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 1251605440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1525859280).

1251605440 is an abundant number, since it is smaller than the sum of its proper divisors (1800113120).

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

1251605440 is a wasteful number, since it uses less digits than its factorization.

1251605440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630 (or 620 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 1251605440 is about 35378.0361241265. The cubic root of 1251605440 is about 1077.6783231367.

Adding to 1251605440 its reverse (445061521), we get a palindrome (1696666961).

The spelling of 1251605440 in words is "one billion, two hundred fifty-one million, six hundred five thousand, four hundred forty".