1991455910 has 16 divisors (see below), whose sum is σ = 3645378000. Its totient is φ = 783080736.

The previous prime is 1991455909. The next prime is 1991455913. The reversal of 1991455910 is 195541991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991455913) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1687085 + ... + 1688264.

It is an arithmetic number, because the mean of its divisors is an integer number (227836125).

Almost surely, 2^1991455910 is an apocalyptic number.

1991455910 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991455910 is a deficient number, since it is larger than the sum of its proper divisors (1653922090).

1991455910 is a wasteful number, since it uses less digits than its factorization.

1991455910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3375415.

The product of its (nonzero) digits is 72900, while the sum is 44.

The square root of 1991455910 is about 44625.7314785988. The cubic root of 1991455910 is about 1258.1243424485.

The spelling of 1991455910 in words is "one billion, nine hundred ninety-one million, four hundred fifty-five thousand, nine hundred ten".