1661423616 has 208 divisors, whose sum is σ = 5008960320. Its totient is φ = 544112640.

The previous prime is 1661423597. The next prime is 1661423627. The reversal of 1661423616 is 6163241661.

It is a happy number.

1661423616 is a `hidden beast` number, since 1 + 6 + 6 + 14 + 23 + 616 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9179046 + ... + 9179226.

It is an arithmetic number, because the mean of its divisors is an integer number (24081540).

Almost surely, 2^1661423616 is an apocalyptic number.

1661423616 is a gapful number since it is divisible by the number (16) 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 1661423616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2504480160).

1661423616 is an abundant number, since it is smaller than the sum of its proper divisors (3347536704).

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

1661423616 is an equidigital number, since it uses as much as digits as its factorization.

1661423616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297 (or 269 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 1661423616 is about 40760.5644710669. The cubic root of 1661423616 is about 1184.3865307260.

The spelling of 1661423616 in words is "one billion, six hundred sixty-one million, four hundred twenty-three thousand, six hundred sixteen".