51840381 has 4 divisors (see below), whose sum is σ = 69120512. Its totient is φ = 34560252.

The previous prime is 51840377. The next prime is 51840407. The reversal of 51840381 is 18304815.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 51840381 - 2² = 51840377 is a prime.

It is a super-2 number, since 2×51840381² = 5374850204450322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51840331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8640061 + ... + 8640066.

It is an arithmetic number, because the mean of its divisors is an integer number (17280128).

Almost surely, 2^51840381 is an apocalyptic number.

It is an amenable number.

51840381 is a deficient number, since it is larger than the sum of its proper divisors (17280131).

51840381 is a wasteful number, since it uses less digits than its factorization.

51840381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17280130.

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 51840381 is about 7200.0264582847. The cubic root of 51840381 is about 372.8688141810.

The spelling of 51840381 in words is "fifty-one million, eight hundred forty thousand, three hundred eighty-one".