1261155 has 16 divisors (see below), whose sum is σ = 2306304. Its totient is φ = 576480.

The previous prime is 1261133. The next prime is 1261157. The reversal of 1261155 is 5511621.

It is not a de Polignac number, because 1261155 - 2⁸ = 1260899 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

1261155 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1261157) 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, 5901 + ... + 6110.

It is an arithmetic number, because the mean of its divisors is an integer number (144144).

2^1261155 is an apocalyptic number.

1261155 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1261155 is a deficient number, since it is larger than the sum of its proper divisors (1045149).

1261155 is a wasteful number, since it uses less digits than its factorization.

1261155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12026.

The product of its digits is 300, while the sum is 21.

The square root of 1261155 is about 1123.0115760757. The cubic root of 1261155 is about 108.0412222612.

Adding to 1261155 its reverse (5511621), we get a palindrome (6772776).

It can be divided in two parts, 126 and 1155, that multiplied together give a triangular number (145530 = T₅₃₉).

The spelling of 1261155 in words is "one million, two hundred sixty-one thousand, one hundred fifty-five".