51648981 has 4 divisors (see below), whose sum is σ = 68865312. Its totient is φ = 34432652.

The previous prime is 51648959. The next prime is 51648997. The reversal of 51648981 is 18984615.

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 a cyclic number.

It is not a de Polignac number, because 51648981 - 2⁷ = 51648853 is a prime.

It is a super-3 number, since 3×51648981³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51648901) 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, 8608161 + ... + 8608166.

It is an arithmetic number, because the mean of its divisors is an integer number (17216328).

Almost surely, 2^51648981 is an apocalyptic number.

It is an amenable number.

51648981 is a deficient number, since it is larger than the sum of its proper divisors (17216331).

51648981 is a wasteful number, since it uses less digits than its factorization.

51648981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17216330.

The product of its digits is 69120, while the sum is 42.

The square root of 51648981 is about 7186.7225492571. The cubic root of 51648981 is about 372.4093583039.

The spelling of 51648981 in words is "fifty-one million, six hundred forty-eight thousand, nine hundred eighty-one".