51218409 has 16 divisors (see below), whose sum is σ = 75049920. Its totient is φ = 30812160.

The previous prime is 51218359. The next prime is 51218423. The reversal of 51218409 is 90481215.

It is a happy number.

It is not a de Polignac number, because 51218409 - 2¹² = 51214313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51214409) 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, 1144 + ... + 10185.

It is an arithmetic number, because the mean of its divisors is an integer number (4690620).

Almost surely, 2^51218409 is an apocalyptic number.

It is an amenable number.

51218409 is a deficient number, since it is larger than the sum of its proper divisors (23831511).

51218409 is a wasteful number, since it uses less digits than its factorization.

51218409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11480.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 51218409 is about 7156.7037803726. The cubic root of 51218409 is about 371.3716050067.

It can be divided in two parts, 5121 and 8409, that added together give a triangular number (13530 = T₁₆₄).

The spelling of 51218409 in words is "fifty-one million, two hundred eighteen thousand, four hundred nine".