65621009 has 2 divisors, whose sum is σ = 65621010. Its totient is φ = 65621008.

The previous prime is 65620999. The next prime is 65621011. The reversal of 65621009 is 90012656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36966400 + 28654609 = 6080^2 + 5353^2 .

It is a cyclic number.

It is not a de Polignac number, because 65621009 - 2¹² = 65616913 is a prime.

It is a super-2 number, since 2×65621009² = 8612233644356162, which contains 22 as substring.

Together with 65621011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (65621069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32810504 + 32810505.

It is an arithmetic number, because the mean of its divisors is an integer number (32810505).

Almost surely, 2^65621009 is an apocalyptic number.

It is an amenable number.

65621009 is a deficient number, since it is larger than the sum of its proper divisors (1).

65621009 is an equidigital number, since it uses as much as digits as its factorization.

65621009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 65621009 is about 8100.6795393967. The cubic root of 65621009 is about 403.3489845864.

The spelling of 65621009 in words is "sixty-five million, six hundred twenty-one thousand, nine".