1225121551 has 4 divisors (see below), whose sum is σ = 1241904112. Its totient is φ = 1208338992.

The previous prime is 1225121483. The next prime is 1225121567. The reversal of 1225121551 is 1551215221.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1225121551 - 2⁷ = 1225121423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1225121351) 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, 8391171 + ... + 8391316.

It is an arithmetic number, because the mean of its divisors is an integer number (310476028).

Almost surely, 2^1225121551 is an apocalyptic number.

1225121551 is a deficient number, since it is larger than the sum of its proper divisors (16782561).

1225121551 is an equidigital number, since it uses as much as digits as its factorization.

1225121551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16782560.

The product of its digits is 1000, while the sum is 25.

The square root of 1225121551 is about 35001.7363997845. The cubic root of 1225121551 is about 1070.0228693397.

Adding to 1225121551 its reverse (1551215221), we get a palindrome (2776336772).

The spelling of 1225121551 in words is "one billion, two hundred twenty-five million, one hundred twenty-one thousand, five hundred fifty-one".