1661618400 has 288 divisors, whose sum is σ = 6133357440. Its totient is φ = 387348480.

The previous prime is 1661618363. The next prime is 1661618407. The reversal of 1661618400 is 48161661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661618407) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 591399 + ... + 594201.

It is an arithmetic number, because the mean of its divisors is an integer number (21296380).

Almost surely, 2^1661618400 is an apocalyptic number.

1661618400 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 1661618400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3066678720).

1661618400 is an abundant number, since it is smaller than the sum of its proper divisors (4471739040).

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

1661618400 is a wasteful number, since it uses less digits than its factorization.

1661618400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2858 (or 2845 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 1661618400 is about 40762.9537693234. The cubic root of 1661618400 is about 1184.4328144328.

The spelling of 1661618400 in words is "one billion, six hundred sixty-one million, six hundred eighteen thousand, four hundred".