1661426550 has 144 divisors (see below), whose sum is σ = 5122252512. Its totient is φ = 378201600.

The previous prime is 1661426549. The next prime is 1661426579. The reversal of 1661426550 is 556241661.

1661426550 is a `hidden beast` number, since 1 + 6 + 61 + 42 + 6 + 550 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 884212 + ... + 886088.

It is an arithmetic number, because the mean of its divisors is an integer number (35571198).

Almost surely, 2^1661426550 is an apocalyptic number.

1661426550 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 1661426550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2561126256).

1661426550 is an abundant number, since it is smaller than the sum of its proper divisors (3460825962).

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

1661426550 is a wasteful number, since it uses less digits than its factorization.

1661426550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2183 (or 2175 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 1661426550 is about 40760.6004617204. The cubic root of 1661426550 is about 1184.3872279168.

The spelling of 1661426550 in words is "one billion, six hundred sixty-one million, four hundred twenty-six thousand, five hundred fifty".