51581409 has 16 divisors (see below), whose sum is σ = 78977280. Its totient is φ = 29615760.

The previous prime is 51581393. The next prime is 51581423. The reversal of 51581409 is 90418515.

51581409 = 462² + 463² + ... + 632².

It is not a de Polignac number, because 51581409 - 2⁴ = 51581393 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 51581409.

It is not an unprimeable number, because it can be changed into a prime (51581809) 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 15 ways as a sum of consecutive naturals, for example, 40507 + ... + 41760.

It is an arithmetic number, because the mean of its divisors is an integer number (4936080).

Almost surely, 2^51581409 is an apocalyptic number.

It is an amenable number.

51581409 is a deficient number, since it is larger than the sum of its proper divisors (27395871).

51581409 is a wasteful number, since it uses less digits than its factorization.

51581409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82300.

The product of its (nonzero) digits is 7200, while the sum is 33.

The square root of 51581409 is about 7182.0198412424. The cubic root of 51581409 is about 372.2468805756.

The spelling of 51581409 in words is "fifty-one million, five hundred eighty-one thousand, four hundred nine".