1666557541 has 4 divisors (see below), whose sum is σ = 1818062784. Its totient is φ = 1515052300.

The previous prime is 1666557523. The next prime is 1666557559. The reversal of 1666557541 is 1457556661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (1666557523) and next prime (1666557559).

It is a cyclic number.

It is not a de Polignac number, because 1666557541 - 2¹³ = 1666549349 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1666557491 and 1666557500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666554541) 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, 75752605 + ... + 75752626.

It is an arithmetic number, because the mean of its divisors is an integer number (454515696).

Almost surely, 2^1666557541 is an apocalyptic number.

1666557541 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1666557541 is a deficient number, since it is larger than the sum of its proper divisors (151505243).

1666557541 is a wasteful number, since it uses less digits than its factorization.

1666557541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151505242.

The product of its digits is 756000, while the sum is 46.

The square root of 1666557541 is about 40823.4925135026. The cubic root of 1666557541 is about 1185.6052243750.

The spelling of 1666557541 in words is "one billion, six hundred sixty-six million, five hundred fifty-seven thousand, five hundred forty-one".