1010019991 has 4 divisors (see below), whose sum is σ = 1033508872. Its totient is φ = 986531112.

The previous prime is 1010019979. The next prime is 1010020003. The reversal of 1010019991 is 1999100101.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1010019979) and next prime (1010020003).

It is not a de Polignac number, because 1010019991 - 2⁷ = 1010019863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1010019911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11744376 + ... + 11744461.

It is an arithmetic number, because the mean of its divisors is an integer number (258377218).

Almost surely, 2^1010019991 is an apocalyptic number.

1010019991 is a deficient number, since it is larger than the sum of its proper divisors (23488881).

1010019991 is an equidigital number, since it uses as much as digits as its factorization.

1010019991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23488880.

The product of its (nonzero) digits is 729, while the sum is 31.

The square root of 1010019991 is about 31780.8116793766. The cubic root of 1010019991 is about 1003.3289031076.

The spelling of 1010019991 in words is "one billion, ten million, nineteen thousand, nine hundred ninety-one".