1251640 has 64 divisors (see below), whose sum is σ = 3175200. Its totient is φ = 440832.

The previous prime is 1251583. The next prime is 1251641. The reversal of 1251640 is 461521.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251641) 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, 15039 + ... + 15121.

2^1251640 is an apocalyptic number.

1251640 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 1251640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1587600).

1251640 is an abundant number, since it is smaller than the sum of its proper divisors (1923560).

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

1251640 is a wasteful number, since it uses less digits than its factorization.

1251640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 1251640 is about 1118.7671786391. The cubic root of 1251640 is about 107.7688242189.

It can be divided in two parts, 1251 and 640, that added together give a triangular number (1891 = T₆₁).

The spelling of 1251640 in words is "one million, two hundred fifty-one thousand, six hundred forty".