65231721 has 6 divisors (see below), whose sum is σ = 94223610. Its totient is φ = 43487808.

The previous prime is 65231713. The next prime is 65231767. The reversal of 65231721 is 12713256.

It is a happy number.

65231721 is a `hidden beast` number, since 652 + 3 + 1 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 45968400 + 19263321 = 6780^2 + 4389^2 .

It is not a de Polignac number, because 65231721 - 2³ = 65231713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (65231791) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3623976 + ... + 3623993.

It is an arithmetic number, because the mean of its divisors is an integer number (15703935).

Almost surely, 2^65231721 is an apocalyptic number.

It is an amenable number.

65231721 is a deficient number, since it is larger than the sum of its proper divisors (28991889).

65231721 is a wasteful number, since it uses less digits than its factorization.

65231721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7247975 (or 7247972 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 65231721 is about 8076.6156897552. The cubic root of 65231721 is about 402.5497972158.

Adding to 65231721 its reverse (12713256), we get a palindrome (77944977).

The spelling of 65231721 in words is "sixty-five million, two hundred thirty-one thousand, seven hundred twenty-one".