166561503 has 4 divisors (see below), whose sum is σ = 222082008. Its totient is φ = 111041000.

The previous prime is 166561463. The next prime is 166561511. The reversal of 166561503 is 305165661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 166561503 - 2¹² = 166557407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166561523) 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, 27760248 + ... + 27760253.

It is an arithmetic number, because the mean of its divisors is an integer number (55520502).

Almost surely, 2^166561503 is an apocalyptic number.

166561503 is a deficient number, since it is larger than the sum of its proper divisors (55520505).

166561503 is an equidigital number, since it uses as much as digits as its factorization.

166561503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55520504.

The product of its (nonzero) digits is 16200, while the sum is 33.

The square root of 166561503 is about 12905.8708733661. The cubic root of 166561503 is about 550.2054362035.

The spelling of 166561503 in words is "one hundred sixty-six million, five hundred sixty-one thousand, five hundred three".