1551666 has 8 divisors (see below), whose sum is σ = 3103344. Its totient is φ = 517220.

The previous prime is 1551661. The next prime is 1551677. The reversal of 1551666 is 6661551.

It is a sphenic number, since it is the product of 3 distinct primes.

1551666 is an admirable number.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (1551661) 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, 129300 + ... + 129311.

It is an arithmetic number, because the mean of its divisors is an integer number (387918).

2^1551666 is an apocalyptic number.

1551666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1551666 is a wasteful number, since it uses less digits than its factorization.

1551666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258616.

The product of its digits is 5400, while the sum is 30.

The square root of 1551666 is about 1245.6588618077. The cubic root of 1551666 is about 115.7709013782.

It can be divided in two parts, 15 and 51666, that added together give a triangular number (51681 = T₃₂₁).

The spelling of 1551666 in words is "one million, five hundred fifty-one thousand, six hundred sixty-six".