51111821 has 16 divisors (see below), whose sum is σ = 53891904. Its totient is φ = 48432384.

The previous prime is 51111787. The next prime is 51111857. The reversal of 51111821 is 12811115.

It is a cyclic number.

It is not a de Polignac number, because 51111821 - 2¹⁴ = 51095437 is a prime.

It is a super-2 number, since 2×51111821² = 5224836491872082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51111793 and 51111802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51110821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 325475 + ... + 325631.

It is an arithmetic number, because the mean of its divisors is an integer number (3368244).

Almost surely, 2^51111821 is an apocalyptic number.

It is an amenable number.

51111821 is a deficient number, since it is larger than the sum of its proper divisors (2780083).

51111821 is a wasteful number, since it uses less digits than its factorization.

51111821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 380.

The product of its digits is 80, while the sum is 20.

The square root of 51111821 is about 7149.2531777802. The cubic root of 51111821 is about 371.1138119738.

Adding to 51111821 its reverse (12811115), we get a palindrome (63922936).

The spelling of 51111821 in words is "fifty-one million, one hundred eleven thousand, eight hundred twenty-one".