1661497920 has 336 divisors, whose sum is σ = 6190853760. Its totient is φ = 423346176.

The previous prime is 1661497891. The next prime is 1661497939. The reversal of 1661497920 is 297941661.

1661497920 is a `hidden beast` number, since 1 + 6 + 614 + 9 + 7 + 9 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1788016 + ... + 1788944.

It is an arithmetic number, because the mean of its divisors is an integer number (18425160).

Almost surely, 2^1661497920 is an apocalyptic number.

1661497920 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 1661497920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3095426880).

1661497920 is an abundant number, since it is smaller than the sum of its proper divisors (4529355840).

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

1661497920 is an equidigital number, since it uses as much as digits as its factorization.

1661497920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 984 (or 962 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 1661497920 is about 40761.4759300985. The cubic root of 1661497920 is about 1184.4041869384.

The spelling of 1661497920 in words is "one billion, six hundred sixty-one million, four hundred ninety-seven thousand, nine hundred twenty".