65523781 has 16 divisors (see below), whose sum is σ = 70479360. Its totient is φ = 60808320.

The previous prime is 65523779. The next prime is 65523811. The reversal of 65523781 is 18732556.

It is a 4-Lehmer number, since φ(65523781) divides (65523781-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 65523781 - 2¹ = 65523779 is a prime.

It is a super-2 number, since 2×65523781² = 8586731753071922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 65523781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65523721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70840 + ... + 71758.

It is an arithmetic number, because the mean of its divisors is an integer number (4404960).

It is a Poulet number, since it divides 2^65523780-1.

Almost surely, 2^65523781 is an apocalyptic number.

It is an amenable number.

65523781 is a deficient number, since it is larger than the sum of its proper divisors (4955579).

65523781 is a wasteful number, since it uses less digits than its factorization.

65523781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044.

The product of its digits is 50400, while the sum is 37.

The square root of 65523781 is about 8094.6760898754. The cubic root of 65523781 is about 403.1496774830.

The spelling of 65523781 in words is "sixty-five million, five hundred twenty-three thousand, seven hundred eighty-one".