1261890 has 48 divisors (see below), whose sum is σ = 3751488. Its totient is φ = 288288.

The previous prime is 1261889. The next prime is 1261891. The reversal of 1261890 is 981621.

1261890 = 50² + 51² + ... + 157².

It is an interprime number because it is at equal distance from previous prime (1261889) and next prime (1261891).

It is not an unprimeable number, because it can be changed into a prime (1261891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 372 + ... + 1631.

It is an arithmetic number, because the mean of its divisors is an integer number (78156).

2^1261890 is an apocalyptic number.

1261890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1261890 is an abundant number, since it is smaller than the sum of its proper divisors (2489598).

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

1261890 is a wasteful number, since it uses less digits than its factorization.

1261890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2023 (or 2020 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 1261890 is about 1123.3387734784. The cubic root of 1261890 is about 108.0622069609.

It can be divided in two parts, 126 and 1890, that added together give a triangular number (2016 = T₆₃).

The spelling of 1261890 in words is "one million, two hundred sixty-one thousand, eight hundred ninety".