1251781040 has 40 divisors (see below), whose sum is σ = 2989057200. Its totient is φ = 487178496.

The previous prime is 1251781007. The next prime is 1251781051. The reversal of 1251781040 is 401871521.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 1251780994 and 1251781012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208490 + ... + 214409.

It is an arithmetic number, because the mean of its divisors is an integer number (74726430).

Almost surely, 2^1251781040 is an apocalyptic number.

1251781040 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1251781040 is an abundant number, since it is smaller than the sum of its proper divisors (1737276160).

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

1251781040 is a wasteful number, since it uses less digits than its factorization.

1251781040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422949 (or 422943 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 29.

The square root of 1251781040 is about 35380.5178028813. The cubic root of 1251781040 is about 1077.7287201330.

The spelling of 1251781040 in words is "one billion, two hundred fifty-one million, seven hundred eighty-one thousand, forty".