19958991 has 16 divisors (see below), whose sum is σ = 28769664. Its totient is φ = 12235104.

The previous prime is 19958977. The next prime is 19958999. The reversal of 19958991 is 19985991.

It is not a de Polignac number, because 19958991 - 2⁵ = 19958959 is a prime.

It is a super-2 number, since 2×19958991² = 796722643476162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19958999) 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, 11140 + ... + 12806.

It is an arithmetic number, because the mean of its divisors is an integer number (1798104).

Almost surely, 2^19958991 is an apocalyptic number.

19958991 is a deficient number, since it is larger than the sum of its proper divisors (8810673).

19958991 is a wasteful number, since it uses less digits than its factorization.

19958991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1990.

The product of its digits is 262440, while the sum is 51.

The square root of 19958991 is about 4467.5486567020. The cubic root of 19958991 is about 271.2561087909.

Subtracting 19958991 from its reverse (19985991), we obtain a cube (27000 = 30³).

The spelling of 19958991 in words is "nineteen million, nine hundred fifty-eight thousand, nine hundred ninety-one".