1251022121 has 4 divisors (see below), whose sum is σ = 1252303572. Its totient is φ = 1249740672.

The previous prime is 1251022109. The next prime is 1251022153. The reversal of 1251022121 is 1212201521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1212201521 = 17599 ⋅68879.

It can be written as a sum of positive squares in 2 ways, for example, as 1040772121 + 210250000 = 32261^2 + 14500^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251022121 - 2¹⁸ = 1250759977 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1251022121.

It is not an unprimeable number, because it can be changed into a prime (1251022021) 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, 639260 + ... + 641213.

It is an arithmetic number, because the mean of its divisors is an integer number (313075893).

Almost surely, 2^1251022121 is an apocalyptic number.

It is an amenable number.

1251022121 is a deficient number, since it is larger than the sum of its proper divisors (1281451).

1251022121 is an equidigital number, since it uses as much as digits as its factorization.

1251022121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1281450.

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 1251022121 is about 35369.7910793943. The cubic root of 1251022121 is about 1077.5108774156.

Adding to 1251022121 its reverse (1212201521), we get a palindrome (2463223642).

The spelling of 1251022121 in words is "one billion, two hundred fifty-one million, twenty-two thousand, one hundred twenty-one".