1261663 has 16 divisors (see below), whose sum is σ = 1451296. Its totient is φ = 1088640.

The previous prime is 1261649. The next prime is 1261697. The reversal of 1261663 is 3661621.

It is a cyclic number.

It is not a de Polignac number, because 1261663 - 2¹³ = 1253471 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261643) 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, 20653 + ... + 20713.

It is an arithmetic number, because the mean of its divisors is an integer number (90706).

2^1261663 is an apocalyptic number.

1261663 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

1261663 is a deficient number, since it is larger than the sum of its proper divisors (189633).

1261663 is a wasteful number, since it uses less digits than its factorization.

1261663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154.

The product of its digits is 1296, while the sum is 25.

The square root of 1261663 is about 1123.2377308477. The cubic root of 1261663 is about 108.0557268419.

The spelling of 1261663 in words is "one million, two hundred sixty-one thousand, six hundred sixty-three".