1261840 has 20 divisors (see below), whose sum is σ = 2933964. Its totient is φ = 504704.

The previous prime is 1261837. The next prime is 1261861. The reversal of 1261840 is 481621.

It can be written as a sum of positive squares in 2 ways, for example, as 595984 + 665856 = 772^2 + 816^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7807 + ... + 7966.

2^1261840 is an apocalyptic number.

1261840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261840 is an abundant number, since it is smaller than the sum of its proper divisors (1672124).

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

1261840 is a wasteful number, since it uses less digits than its factorization.

1261840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15786 (or 15780 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 1261840 is about 1123.3165181729. The cubic root of 1261840 is about 108.0607796886.

It can be divided in two parts, 1261 and 840, that multiplied together give a triangular number (1059240 = T₁₄₅₅).

The spelling of 1261840 in words is "one million, two hundred sixty-one thousand, eight hundred forty".