991664019 has 16 divisors (see below), whose sum is σ = 1519792800. Its totient is φ = 638311968.

The previous prime is 991663993. The next prime is 991664033. The reversal of 991664019 is 910466199.

It is not a de Polignac number, because 991664019 - 2⁷ = 991663891 is a prime.

It is a super-2 number, since 2×991664019² = 1966795053158464722, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (991664039) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 632464 + ... + 634029.

It is an arithmetic number, because the mean of its divisors is an integer number (94987050).

Almost surely, 2^991664019 is an apocalyptic number.

991664019 is a deficient number, since it is larger than the sum of its proper divisors (528128781).

991664019 is a wasteful number, since it uses less digits than its factorization.

991664019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1266531 (or 1266525 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The square root of 991664019 is about 31490.6973406433. The cubic root of 991664019 is about 997.2135827570.

The spelling of 991664019 in words is "nine hundred ninety-one million, six hundred sixty-four thousand, nineteen".