51211551 has 4 divisors (see below), whose sum is σ = 68282072. Its totient is φ = 34141032.

The previous prime is 51211543. The next prime is 51211553. The reversal of 51211551 is 15511215.

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

It is not a de Polignac number, because 51211551 - 2³ = 51211543 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 (51211553) 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, 8535256 + ... + 8535261.

It is an arithmetic number, because the mean of its divisors is an integer number (17070518).

Almost surely, 2^51211551 is an apocalyptic number.

51211551 is a deficient number, since it is larger than the sum of its proper divisors (17070521).

51211551 is a wasteful number, since it uses less digits than its factorization.

51211551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17070520.

The product of its digits is 250, while the sum is 21.

The square root of 51211551 is about 7156.2246331428. The cubic root of 51211551 is about 371.3550290646.

Adding to 51211551 its reverse (15511215), we get a palindrome (66722766).

The spelling of 51211551 in words is "fifty-one million, two hundred eleven thousand, five hundred fifty-one".