1521666165 has 16 divisors (see below), whose sum is σ = 2444371776. Its totient is φ = 808320000.

The previous prime is 1521666151. The next prime is 1521666173. The reversal of 1521666165 is 5616661251.

It is not a de Polignac number, because 1521666165 - 2⁸ = 1521665909 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 198316 + ... + 205845.

It is an arithmetic number, because the mean of its divisors is an integer number (152773236).

Almost surely, 2^1521666165 is an apocalyptic number.

1521666165 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1521666165 is a deficient number, since it is larger than the sum of its proper divisors (922705611).

1521666165 is a wasteful number, since it uses less digits than its factorization.

1521666165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404420.

The product of its digits is 64800, while the sum is 39.

The square root of 1521666165 is about 39008.5396419810. The cubic root of 1521666165 is about 1150.1993769000.

The spelling of 1521666165 in words is "one billion, five hundred twenty-one million, six hundred sixty-six thousand, one hundred sixty-five".