1660506221 has 4 divisors (see below), whose sum is σ = 1811461344. Its totient is φ = 1509551100.

The previous prime is 1660506173. The next prime is 1660506223. The reversal of 1660506221 is 1226050661.

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 a cyclic number.

It is not a de Polignac number, because 1660506221 - 2¹⁸ = 1660244077 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1660506223) 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, 75477545 + ... + 75477566.

It is an arithmetic number, because the mean of its divisors is an integer number (452865336).

Almost surely, 2^1660506221 is an apocalyptic number.

1660506221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1660506221 is a deficient number, since it is larger than the sum of its proper divisors (150955123).

1660506221 is a wasteful number, since it uses less digits than its factorization.

1660506221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150955122.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 1660506221 is about 40749.3094542717. The cubic root of 1660506221 is about 1184.1684947556.

Adding to 1660506221 its reverse (1226050661), we get a palindrome (2886556882).

It can be divided in two parts, 166050 and 6221, that added together give a palindrome (172271).

The spelling of 1660506221 in words is "one billion, six hundred sixty million, five hundred six thousand, two hundred twenty-one".