51809121 has 48 divisors (see below), whose sum is σ = 94057600. Its totient is φ = 27306720.

The previous prime is 51809111. The next prime is 51809129. The reversal of 51809121 is 12190815.

It is not a de Polignac number, because 51809121 - 2⁶ = 51809057 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (51809129) 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, 39486 + ... + 40776.

Almost surely, 2^51809121 is an apocalyptic number.

It is an amenable number.

51809121 is a deficient number, since it is larger than the sum of its proper divisors (42248479).

51809121 is a wasteful number, since it uses less digits than its factorization.

51809121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1331 (or 1314 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 51809121 is about 7197.8553055754. The cubic root of 51809121 is about 372.7938518798.

Adding to 51809121 its reverse (12190815), we get a palindrome (63999936).

The spelling of 51809121 in words is "fifty-one million, eight hundred nine thousand, one hundred twenty-one".