1664641551 has 8 divisors (see below), whose sum is σ = 2220072624. Its totient is φ = 1109485760.

The previous prime is 1664641549. The next prime is 1664641577. The reversal of 1664641551 is 1551464661.

It is a happy number.

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 1664641551 - 2¹ = 1664641549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664641501) 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, 54270 + ... + 79211.

It is an arithmetic number, because the mean of its divisors is an integer number (277509078).

Almost surely, 2^1664641551 is an apocalyptic number.

1664641551 is a deficient number, since it is larger than the sum of its proper divisors (555431073).

1664641551 is a wasteful number, since it uses less digits than its factorization.

1664641551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137641.

The product of its digits is 86400, while the sum is 39.

The square root of 1664641551 is about 40800.0190073485. The cubic root of 1664641551 is about 1185.1506988462.

The spelling of 1664641551 in words is "one billion, six hundred sixty-four million, six hundred forty-one thousand, five hundred fifty-one".