65638421 has 4 divisors (see below), whose sum is σ = 65882700. Its totient is φ = 65394144.

The previous prime is 65638409. The next prime is 65638429. The reversal of 65638421 is 12483656.

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 2515396 + 63123025 = 1586^2 + 7945^2 .

It is a cyclic number.

It is not a de Polignac number, because 65638421 - 2⁶ = 65638357 is a prime.

It is a super-2 number, since 2×65638421² = 8616804622746482, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65638429) 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, 121736 + ... + 122273.

It is an arithmetic number, because the mean of its divisors is an integer number (16470675).

Almost surely, 2^65638421 is an apocalyptic number.

It is an amenable number.

65638421 is a deficient number, since it is larger than the sum of its proper divisors (244279).

65638421 is a wasteful number, since it uses less digits than its factorization.

65638421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244278.

The product of its digits is 34560, while the sum is 35.

The square root of 65638421 is about 8101.7541927659. The cubic root of 65638421 is about 403.3846565536.

The spelling of 65638421 in words is "sixty-five million, six hundred thirty-eight thousand, four hundred twenty-one".