664165541 has 4 divisors (see below), whose sum is σ = 715255212. Its totient is φ = 613075872.

The previous prime is 664165531. The next prime is 664165543. The reversal of 664165541 is 145561466.

It is a happy number.

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 251222500 + 412943041 = 15850^2 + 20321^2 .

It is a cyclic number.

It is not a de Polignac number, because 664165541 - 2⁶ = 664165477 is a prime.

It is a super-2 number, since 2×664165541² = 882231731703645362, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664165495 and 664165504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664165543) 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, 25544816 + ... + 25544841.

It is an arithmetic number, because the mean of its divisors is an integer number (178813803).

Almost surely, 2^664165541 is an apocalyptic number.

It is an amenable number.

664165541 is a deficient number, since it is larger than the sum of its proper divisors (51089671).

664165541 is a wasteful number, since it uses less digits than its factorization.

664165541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51089670.

The product of its digits is 86400, while the sum is 38.

The square root of 664165541 is about 25771.4093716273. The cubic root of 664165541 is about 872.4866284215.

The spelling of 664165541 in words is "six hundred sixty-four million, one hundred sixty-five thousand, five hundred forty-one".