51221155 has 4 divisors (see below), whose sum is σ = 61465392. Its totient is φ = 40976920.

The previous prime is 51221129. The next prime is 51221167. The reversal of 51221155 is 55112215.

It is a happy number.

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

It is not a de Polignac number, because 51221155 - 2⁵ = 51221123 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5122111 + ... + 5122120.

It is an arithmetic number, because the mean of its divisors is an integer number (15366348).

Almost surely, 2^51221155 is an apocalyptic number.

51221155 is a deficient number, since it is larger than the sum of its proper divisors (10244237).

51221155 is a wasteful number, since it uses less digits than its factorization.

51221155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10244236.

The product of its digits is 500, while the sum is 22.

The square root of 51221155 is about 7156.8956258981. The cubic root of 51221155 is about 371.3782417364.

The spelling of 51221155 in words is "fifty-one million, two hundred twenty-one thousand, one hundred fifty-five".