1985197890 has 32 divisors (see below), whose sum is σ = 5130974016. Its totient is φ = 488664000.

The previous prime is 1985197801. The next prime is 1985197913. The reversal of 1985197890 is 987915891.

It is a self number, because there is not a number n which added to its sum of digits gives 1985197890.

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 15 ways as a sum of consecutive naturals, for example, 2544736 + ... + 2545515.

It is an arithmetic number, because the mean of its divisors is an integer number (160342938).

Almost surely, 2^1985197890 is an apocalyptic number.

1985197890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1985197890 is an abundant number, since it is smaller than the sum of its proper divisors (3145776126).

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

1985197890 is a wasteful number, since it uses less digits than its factorization.

1985197890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5090274.

The product of its (nonzero) digits is 1632960, while the sum is 57.

The square root of 1985197890 is about 44555.5595857576. The cubic root of 1985197890 is about 1256.8051017753.

The spelling of 1985197890 in words is "one billion, nine hundred eighty-five million, one hundred ninety-seven thousand, eight hundred ninety".