65999621 has 8 divisors (see below), whose sum is σ = 69396600. Its totient is φ = 62677440.

The previous prime is 65999599. The next prime is 65999639. The reversal of 65999621 is 12699956.

It can be written as a sum of positive squares in 4 ways, for example, as 616225 + 65383396 = 785^2 + 8086^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65999621 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 (65999671) 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, 16886 + ... + 20423.

It is an arithmetic number, because the mean of its divisors is an integer number (8674575).

Almost surely, 2^65999621 is an apocalyptic number.

65999621 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

65999621 is a deficient number, since it is larger than the sum of its proper divisors (3396979).

65999621 is a wasteful number, since it uses less digits than its factorization.

65999621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37399.

The product of its digits is 262440, while the sum is 47.

The square root of 65999621 is about 8124.0150787649. The cubic root of 65999621 is about 404.1232285102.

The spelling of 65999621 in words is "sixty-five million, nine hundred ninety-nine thousand, six hundred twenty-one".