65216381 has 8 divisors (see below), whose sum is σ = 66477144. Its totient is φ = 63961920.

The previous prime is 65216357. The next prime is 65216399. The reversal of 65216381 is 18361256.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1136356 + 64080025 = 1066^2 + 8005^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 65216381 - 2¹⁰ = 65215357 is a prime.

It is a super-2 number, since 2×65216381² = 8506352701474322, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65216321) 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, 22871 + ... + 25563.

It is an arithmetic number, because the mean of its divisors is an integer number (8309643).

Almost surely, 2^65216381 is an apocalyptic number.

65216381 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

65216381 is a deficient number, since it is larger than the sum of its proper divisors (1260763).

65216381 is a wasteful number, since it uses less digits than its factorization.

65216381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3151.

The product of its digits is 8640, while the sum is 32.

The square root of 65216381 is about 8075.6659787289. The cubic root of 65216381 is about 402.5182399820.

The spelling of 65216381 in words is "sixty-five million, two hundred sixteen thousand, three hundred eighty-one".