1019991780 has 36 divisors (see below), whose sum is σ = 3093975612. Its totient is φ = 271997760.

The previous prime is 1019991773. The next prime is 1019991811. The reversal of 1019991780 is 871999101.

It can be written as a sum of positive squares in 2 ways, for example, as 210134016 + 809857764 = 14496^2 + 28458^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 11 ways as a sum of consecutive naturals, for example, 2833131 + ... + 2833490.

It is an arithmetic number, because the mean of its divisors is an integer number (85943767).

Almost surely, 2^1019991780 is an apocalyptic number.

1019991780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1019991780 is an abundant number, since it is smaller than the sum of its proper divisors (2073983832).

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

1019991780 is a wasteful number, since it uses less digits than its factorization.

1019991780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5666636 (or 5666631 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 45.

The square root of 1019991780 is about 31937.3101559915. The cubic root of 1019991780 is about 1006.6200054879.

The spelling of 1019991780 in words is "one billion, nineteen million, nine hundred ninety-one thousand, seven hundred eighty".