65221381 has 8 divisors (see below), whose sum is σ = 66489984. Its totient is φ = 63962640.

The previous prime is 65221369. The next prime is 65221393. The reversal of 65221381 is 18312256.

65221381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (65221369) and next prime (65221393).

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

It is a 4-Lehmer number, since φ(65221381) divides (65221381-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 65221381 - 2⁷ = 65221253 is a prime.

It is a super-2 number, since 2×65221381² = 8507657079094322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65221081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11656 + ... + 16318.

It is an arithmetic number, because the mean of its divisors is an integer number (8311248).

Almost surely, 2^65221381 is an apocalyptic number.

65221381 is the 4663-rd octagonal number.

It is an amenable number.

65221381 is a deficient number, since it is larger than the sum of its proper divisors (1268603).

65221381 is a wasteful number, since it uses less digits than its factorization.

65221381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4931.

The product of its digits is 2880, while the sum is 28.

The square root of 65221381 is about 8075.9755447871. The cubic root of 65221381 is about 402.5285264557.

The spelling of 65221381 in words is "sixty-five million, two hundred twenty-one thousand, three hundred eighty-one".