151666561 has 4 divisors (see below), whose sum is σ = 152574912. Its totient is φ = 150758212.

The previous prime is 151666523. The next prime is 151666583. The reversal of 151666561 is 165666151.

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, and also an emirpimes, since its reverse is a distinct semiprime: 165666151 = 7 ⋅23666593.

It is a cyclic number.

It is not a de Polignac number, because 151666561 - 2¹⁵ = 151633793 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 151666561.

It is not an unprimeable number, because it can be changed into a prime (151666511) 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, 453925 + ... + 454258.

It is an arithmetic number, because the mean of its divisors is an integer number (38143728).

Almost surely, 2^151666561 is an apocalyptic number.

It is an amenable number.

151666561 is a deficient number, since it is larger than the sum of its proper divisors (908351).

151666561 is an equidigital number, since it uses as much as digits as its factorization.

151666561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 908350.

The product of its digits is 32400, while the sum is 37.

The square root of 151666561 is about 12315.2978445509. The cubic root of 151666561 is about 533.2898031746.

The spelling of 151666561 in words is "one hundred fifty-one million, six hundred sixty-six thousand, five hundred sixty-one".