65721621 has 8 divisors (see below), whose sum is σ = 100147264. Its totient is φ = 37555200.

The previous prime is 65721619. The next prime is 65721629. The reversal of 65721621 is 12612756.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 65721621 - 2¹ = 65721619 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65721629) 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, 1564780 + ... + 1564821.

It is an arithmetic number, because the mean of its divisors is an integer number (12518408).

Almost surely, 2^65721621 is an apocalyptic number.

It is an amenable number.

65721621 is a deficient number, since it is larger than the sum of its proper divisors (34425643).

65721621 is a wasteful number, since it uses less digits than its factorization.

65721621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3129611.

The product of its digits is 5040, while the sum is 30.

The square root of 65721621 is about 8106.8872571413. The cubic root of 65721621 is about 403.5550213722. Note that the first 3 decimals are identical.

The spelling of 65721621 in words is "sixty-five million, seven hundred twenty-one thousand, six hundred twenty-one".