65983781 has 8 divisors (see below), whose sum is σ = 67349880. Its totient is φ = 64622272.

The previous prime is 65983777. The next prime is 65983793. The reversal of 65983781 is 18738956.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 13653025 + 52330756 = 3695^2 + 7234^2 .

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 65983781 - 2² = 65983777 is a prime.

It is a super-2 number, since 2×65983781² = 8707718710111922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65983741) 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, 53075 + ... + 54303.

It is an arithmetic number, because the mean of its divisors is an integer number (8418735).

Almost surely, 2^65983781 is an apocalyptic number.

It is an amenable number.

65983781 is a deficient number, since it is larger than the sum of its proper divisors (1366099).

65983781 is a wasteful number, since it uses less digits than its factorization.

65983781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2295.

The product of its digits is 362880, while the sum is 47.

The square root of 65983781 is about 8123.0401328567. The cubic root of 65983781 is about 404.0908958796.

The spelling of 65983781 in words is "sixty-five million, nine hundred eighty-three thousand, seven hundred eighty-one".