51540921 has 8 divisors (see below), whose sum is σ = 76356960. Its totient is φ = 34360596.

The previous prime is 51540911. The next prime is 51540947. The reversal of 51540921 is 12904515.

It is not a de Polignac number, because 51540921 - 2¹⁰ = 51539897 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 1908923 = 51540921 / (5 + 1 + 5 + 4 + 0 + 9 + 2 + 1).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51540911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 954435 + ... + 954488.

It is an arithmetic number, because the mean of its divisors is an integer number (9544620).

Almost surely, 2^51540921 is an apocalyptic number.

It is an amenable number.

51540921 is a deficient number, since it is larger than the sum of its proper divisors (24816039).

51540921 is a wasteful number, since it uses less digits than its factorization.

51540921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1908932 (or 1908926 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 51540921 is about 7179.2005822376. The cubic root of 51540921 is about 372.1494586743.

The spelling of 51540921 in words is "fifty-one million, five hundred forty thousand, nine hundred twenty-one".