1251561270 has 64 divisors (see below), whose sum is σ = 3039001344. Its totient is φ = 329857920.

The previous prime is 1251561247. The next prime is 1251561271. The reversal of 1251561270 is 721651521.

It is a super-2 number, since 2×1251561270² = 3132811225128025800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251561271) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1031184 + ... + 1032396.

It is an arithmetic number, because the mean of its divisors is an integer number (47484396).

Almost surely, 2^1251561270 is an apocalyptic number.

1251561270 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1251561270 is an abundant number, since it is smaller than the sum of its proper divisors (1787440074).

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

1251561270 is a wasteful number, since it uses less digits than its factorization.

1251561270 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1597.

The product of its (nonzero) digits is 4200, while the sum is 30.

The square root of 1251561270 is about 35377.4118612428. The cubic root of 1251561270 is about 1077.6656456560.

The spelling of 1251561270 in words is "one billion, two hundred fifty-one million, five hundred sixty-one thousand, two hundred seventy".