1664635731 has 8 divisors (see below), whose sum is σ = 2421288384. Its totient is φ = 1008870120.

The previous prime is 1664635727. The next prime is 1664635747. The reversal of 1664635731 is 1375364661.

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

It is not a de Polignac number, because 1664635731 - 2² = 1664635727 is a prime.

It is a super-2 number, since 2×1664635731² = 5542024233843808722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1664635751) 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, 25221721 + ... + 25221786.

It is an arithmetic number, because the mean of its divisors is an integer number (302661048).

Almost surely, 2^1664635731 is an apocalyptic number.

1664635731 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1664635731 is a deficient number, since it is larger than the sum of its proper divisors (756652653).

1664635731 is a wasteful number, since it uses less digits than its factorization.

1664635731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50443521.

The product of its digits is 272160, while the sum is 42.

The square root of 1664635731 is about 40799.9476837900. The cubic root of 1664635731 is about 1185.1493176510.

The spelling of 1664635731 in words is "one billion, six hundred sixty-four million, six hundred thirty-five thousand, seven hundred thirty-one".