1661400 has 144 divisors (see below), whose sum is σ = 6093360. Its totient is φ = 403200.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661400 is 41661.

1661400 = T₃₅₂ + T₃₅₃ + ... + T₃₇₆.

1661400 is a `hidden beast` number, since 1 + 661 + 4 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 23365 + ... + 23435.

It is an arithmetic number, because the mean of its divisors is an integer number (42315).

2^1661400 is an apocalyptic number.

1661400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3046680).

1661400 is an abundant number, since it is smaller than the sum of its proper divisors (4431960).

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

1661400 is a wasteful number, since it uses less digits than its factorization.

1661400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 94 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1661400 is about 1288.9530635365. The cubic root of 1661400 is about 118.4380918951.

It can be divided in two parts, 16 and 61400, that added together give a palindrome (61416).

The spelling of 1661400 in words is "one million, six hundred sixty-one thousand, four hundred".