65421623521 has 4 divisors (see below), whose sum is σ = 65432132500. Its totient is φ = 65411114544.

The previous prime is 65421623513. The next prime is 65421623569. The reversal of 65421623521 is 12532612456.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21159775296 + 44261848225 = 145464^2 + 210385^2 .

It is a cyclic number.

It is not a de Polignac number, because 65421623521 - 2³ = 65421623513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65421623321) 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, 5245146 + ... + 5257603.

It is an arithmetic number, because the mean of its divisors is an integer number (16358033125).

Almost surely, 2^65421623521 is an apocalyptic number.

It is an amenable number.

65421623521 is a deficient number, since it is larger than the sum of its proper divisors (10508979).

65421623521 is a wasteful number, since it uses less digits than its factorization.

65421623521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10508978.

The product of its digits is 86400, while the sum is 37.

The spelling of 65421623521 in words is "sixty-five billion, four hundred twenty-one million, six hundred twenty-three thousand, five hundred twenty-one".