19991649 has 8 divisors (see below), whose sum is σ = 26685472. Its totient is φ = 13312800.

The previous prime is 19991639. The next prime is 19991651. The reversal of 19991649 is 94619991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19991649 - 2¹⁶ = 19926113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19991598 and 19991607.

It is not an unprimeable number, because it can be changed into a prime (19991639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127 + ... + 6324.

It is an arithmetic number, because the mean of its divisors is an integer number (3335684).

Almost surely, 2^19991649 is an apocalyptic number.

It is an amenable number.

19991649 is a deficient number, since it is larger than the sum of its proper divisors (6693823).

19991649 is a wasteful number, since it uses less digits than its factorization.

19991649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7487.

The product of its digits is 157464, while the sum is 48.

The square root of 19991649 is about 4471.2021873317. The cubic root of 19991649 is about 271.4039762307.

The spelling of 19991649 in words is "nineteen million, nine hundred ninety-one thousand, six hundred forty-nine".