1661550 has 96 divisors (see below), whose sum is σ = 4821120. Its totient is φ = 374400.

The previous prime is 1661549. The next prime is 1661557. The reversal of 1661550 is 551661.

It is a self number, because there is not a number n which added to its sum of digits gives 1661550.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661557) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 31324 + ... + 31376.

It is an arithmetic number, because the mean of its divisors is an integer number (50220).

2^1661550 is an apocalyptic number.

1661550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2410560).

1661550 is an abundant number, since it is smaller than the sum of its proper divisors (3159570).

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

1661550 is a wasteful number, since it uses less digits than its factorization.

1661550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98 (or 93 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 1661550 is about 1289.0112489812. The cubic root of 1661550 is about 118.4416561941.

It can be divided in two parts, 1661 and 550, that added together give a triangular number (2211 = T₆₆).

The spelling of 1661550 in words is "one million, six hundred sixty-one thousand, five hundred fifty".