51585981 has 4 divisors (see below), whose sum is σ = 68781312. Its totient is φ = 34390652.

The previous prime is 51585949. The next prime is 51585991. The reversal of 51585981 is 18958515.

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 51585981 - 2⁵ = 51585949 is a prime.

It is a super-2 number, since 2×51585981² = 5322226871464722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51585991) 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, 8597661 + ... + 8597666.

It is an arithmetic number, because the mean of its divisors is an integer number (17195328).

Almost surely, 2^51585981 is an apocalyptic number.

It is an amenable number.

51585981 is a deficient number, since it is larger than the sum of its proper divisors (17195331).

51585981 is a wasteful number, since it uses less digits than its factorization.

51585981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17195330.

The product of its digits is 72000, while the sum is 42.

The square root of 51585981 is about 7182.3381290496. The cubic root of 51585981 is about 372.2578784816.

The spelling of 51585981 in words is "fifty-one million, five hundred eighty-five thousand, nine hundred eighty-one".