1261621123 has 4 divisors (see below), whose sum is σ = 1441852720. Its totient is φ = 1081389528.

The previous prime is 1261621103. The next prime is 1261621181. The reversal of 1261621123 is 3211261621.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3211261621 = 251 ⋅12793871.

It is a cyclic number.

It is not a de Polignac number, because 1261621123 - 2¹³ = 1261612931 is a prime.

It is a super-2 number, since 2×1261621123² = 3183375715999562258, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1261621103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90115788 + ... + 90115801.

It is an arithmetic number, because the mean of its divisors is an integer number (360463180).

Almost surely, 2^1261621123 is an apocalyptic number.

1261621123 is a deficient number, since it is larger than the sum of its proper divisors (180231597).

1261621123 is an equidigital number, since it uses as much as digits as its factorization.

1261621123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180231596.

The product of its digits is 864, while the sum is 25.

The square root of 1261621123 is about 35519.3063417629. The cubic root of 1261621123 is about 1080.5453130347.

Adding to 1261621123 its reverse (3211261621), we get a palindrome (4472882744).

The spelling of 1261621123 in words is "one billion, two hundred sixty-one million, six hundred twenty-one thousand, one hundred twenty-three".