1661518420 has 24 divisors (see below), whose sum is σ = 3497155200. Its totient is φ = 663089952.

The previous prime is 1661518393. The next prime is 1661518421. The reversal of 1661518420 is 248151661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661518421) 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 7 ways as a sum of consecutive naturals, for example, 85840 + ... + 103399.

It is an arithmetic number, because the mean of its divisors is an integer number (145714800).

Almost surely, 2^1661518420 is an apocalyptic number.

1661518420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661518420 is an abundant number, since it is smaller than the sum of its proper divisors (1835636780).

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

1661518420 is a wasteful number, since it uses less digits than its factorization.

1661518420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189687 (or 189685 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 1661518420 is about 40761.7273922487. The cubic root of 1661518420 is about 1184.4090580822.

The spelling of 1661518420 in words is "one billion, six hundred sixty-one million, five hundred eighteen thousand, four hundred twenty".