65621639 has 4 divisors (see below), whose sum is σ = 65657856. Its totient is φ = 65585424.

The previous prime is 65621627. The next prime is 65621707. The reversal of 65621639 is 93612656.

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

It is a cyclic number.

It is not a de Polignac number, because 65621639 - 2¹² = 65617543 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65621539) 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, 15239 + ... + 19064.

It is an arithmetic number, because the mean of its divisors is an integer number (16414464).

Almost surely, 2^65621639 is an apocalyptic number.

65621639 is a deficient number, since it is larger than the sum of its proper divisors (36217).

65621639 is a wasteful number, since it uses less digits than its factorization.

65621639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36216.

The product of its digits is 58320, while the sum is 38.

The square root of 65621639 is about 8100.7184249300. The cubic root of 65621639 is about 403.3502753776.

The spelling of 65621639 in words is "sixty-five million, six hundred twenty-one thousand, six hundred thirty-nine".