51118221 has 48 divisors (see below), whose sum is σ = 87628608. Its totient is φ = 26208000.

The previous prime is 51118219. The next prime is 51118247. The reversal of 51118221 is 12281115.

It is not a de Polignac number, because 51118221 - 2¹ = 51118219 is a prime.

It is a super-2 number, since 2×51118221² = 5226145036409682, which contains 22 as substring.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51118211) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 163161 + ... + 163473.

It is an arithmetic number, because the mean of its divisors is an integer number (1825596).

Almost surely, 2^51118221 is an apocalyptic number.

It is an amenable number.

51118221 is a deficient number, since it is larger than the sum of its proper divisors (36510387).

51118221 is a wasteful number, since it uses less digits than its factorization.

51118221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442 (or 435 counting only the distinct ones).

The product of its digits is 160, while the sum is 21.

The square root of 51118221 is about 7149.7007629690. The cubic root of 51118221 is about 371.1293010800.

Adding to 51118221 its reverse (12281115), we get a palindrome (63399336).

The spelling of 51118221 in words is "fifty-one million, one hundred eighteen thousand, two hundred twenty-one".