51135409 has 4 divisors (see below), whose sum is σ = 55068916. Its totient is φ = 47201904.

The previous prime is 51135397. The next prime is 51135419. The reversal of 51135409 is 90453115.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90453115 = 5 ⋅18090623.

It can be written as a sum of positive squares in 2 ways, for example, as 31528225 + 19607184 = 5615^2 + 4428^2 .

It is a cyclic number.

It is not a de Polignac number, because 51135409 - 2⁵ = 51135377 is a prime.

It is a super-2 number, since 2×51135409² = 5229660107194562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51135419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1966734 + ... + 1966759.

It is an arithmetic number, because the mean of its divisors is an integer number (13767229).

Almost surely, 2^51135409 is an apocalyptic number.

It is an amenable number.

51135409 is a deficient number, since it is larger than the sum of its proper divisors (3933507).

51135409 is a wasteful number, since it uses less digits than its factorization.

51135409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3933506.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 51135409 is about 7150.9026702928. The cubic root of 51135409 is about 371.1708926135.

It can be divided in two parts, 51 and 135409, that added together give a triangular number (135460 = T₅₂₀).

The spelling of 51135409 in words is "fifty-one million, one hundred thirty-five thousand, four hundred nine".