51221111 has 4 divisors (see below), whose sum is σ = 51271824. Its totient is φ = 51170400.

The previous prime is 51221101. The next prime is 51221123. The reversal of 51221111 is 11112215.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11112215 = 5 ⋅2222443.

It is a cyclic number.

It is not a de Polignac number, because 51221111 - 2¹⁰ = 51220087 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 (51221101) 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, 23810 + ... + 25871.

It is an arithmetic number, because the mean of its divisors is an integer number (12817956).

Almost surely, 2^51221111 is an apocalyptic number.

51221111 is a deficient number, since it is larger than the sum of its proper divisors (50713).

51221111 is a wasteful number, since it uses less digits than its factorization.

51221111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50712.

The product of its digits is 20, while the sum is 14.

The square root of 51221111 is about 7156.8925519390. The cubic root of 51221111 is about 371.3781353959.

Adding to 51221111 its reverse (11112215), we get a palindrome (62333326).

The spelling of 51221111 in words is "fifty-one million, two hundred twenty-one thousand, one hundred eleven".