1261690 has 16 divisors (see below), whose sum is σ = 2284200. Its totient is φ = 501760.

The previous prime is 1261649. The next prime is 1261697. The reversal of 1261690 is 961621.

It can be written as a sum of positive squares in 4 ways, for example, as 1138489 + 123201 = 1067^2 + 351^2 .

It is a super-2 number, since 2×1261690² = 3183723312200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1261697) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2586 + ... + 3034.

2^1261690 is an apocalyptic number.

1261690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1261690 is the 562-nd decagonal number.

1261690 is a deficient number, since it is larger than the sum of its proper divisors (1022510).

1261690 is a wasteful number, since it uses less digits than its factorization.

1261690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 1261690 is about 1123.2497496105. The cubic root of 1261690 is about 108.0564976457.

The spelling of 1261690 in words is "one million, two hundred sixty-one thousand, six hundred ninety".