51563981 has 8 divisors (see below), whose sum is σ = 59306880. Its totient is φ = 43915248.

The previous prime is 51563957. The next prime is 51563987. The reversal of 51563981 is 18936515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51563981 - 2⁶ = 51563917 is a prime.

It is a super-2 number, since 2×51563981² = 5317688273136722, 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 (51563987) 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, 22361 + ... + 24558.

It is an arithmetic number, because the mean of its divisors is an integer number (7413360).

Almost surely, 2^51563981 is an apocalyptic number.

It is an amenable number.

51563981 is a deficient number, since it is larger than the sum of its proper divisors (7742899).

51563981 is a wasteful number, since it uses less digits than its factorization.

51563981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47083.

The product of its digits is 32400, while the sum is 38.

The square root of 51563981 is about 7180.8064310354. The cubic root of 51563981 is about 372.2049517131.

The spelling of 51563981 in words is "fifty-one million, five hundred sixty-three thousand, nine hundred eighty-one".