65538621 has 24 divisors (see below), whose sum is σ = 101382840. Its totient is φ = 40651776.

The previous prime is 65538611. The next prime is 65538647. The reversal of 65538621 is 12683556.

65538621 is a `hidden beast` number, since 6 + 553 + 86 + 21 = 666.

65538621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 15327225 + 50211396 = 3915^2 + 7086^2 .

It is not a de Polignac number, because 65538621 - 2⁵ = 65538589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65538601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11211 + ... + 16023.

It is an arithmetic number, because the mean of its divisors is an integer number (4224285).

Almost surely, 2^65538621 is an apocalyptic number.

It is an amenable number.

65538621 is a deficient number, since it is larger than the sum of its proper divisors (35844219).

65538621 is a wasteful number, since it uses less digits than its factorization.

65538621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4925 (or 4922 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 65538621 is about 8095.5926898529. The cubic root of 65538621 is about 403.1801106556.

The spelling of 65538621 in words is "sixty-five million, five hundred thirty-eight thousand, six hundred twenty-one".