1664662561 has 8 divisors (see below), whose sum is σ = 1756188000. Its totient is φ = 1573528320.

The previous prime is 1664662547. The next prime is 1664662577. The reversal of 1664662561 is 1652664661.

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

It is not a de Polignac number, because 1664662561 - 2⁵ = 1664662529 is a prime.

It is a super-2 number, since 2×1664662561² = 5542202883990157442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664662501) 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, 89035 + ... + 106096.

It is an arithmetic number, because the mean of its divisors is an integer number (219523500).

Almost surely, 2^1664662561 is an apocalyptic number.

It is an amenable number.

1664662561 is a deficient number, since it is larger than the sum of its proper divisors (91525439).

1664662561 is a wasteful number, since it uses less digits than its factorization.

1664662561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195599.

The product of its digits is 311040, while the sum is 43.

The square root of 1664662561 is about 40800.2764819063. The cubic root of 1664662561 is about 1185.1556848869.

It can be divided in two parts, 1664 and 662561, that added together give a square (664225 = 815²).

The spelling of 1664662561 in words is "one billion, six hundred sixty-four million, six hundred sixty-two thousand, five hundred sixty-one".