19495991 has 4 divisors (see below), whose sum is σ = 20642832. Its totient is φ = 18349152.

The previous prime is 19495981. The next prime is 19496021. The reversal of 19495991 is 19959491.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19959491 = 1151 ⋅17341.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19495991 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 (19495921) 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, 573395 + ... + 573428.

It is an arithmetic number, because the mean of its divisors is an integer number (5160708).

Almost surely, 2^19495991 is an apocalyptic number.

19495991 is a deficient number, since it is larger than the sum of its proper divisors (1146841).

19495991 is a wasteful number, since it uses less digits than its factorization.

19495991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1146840.

The product of its digits is 131220, while the sum is 47.

The square root of 19495991 is about 4415.4264799677. The cubic root of 19495991 is about 269.1421837851.

The spelling of 19495991 in words is "nineteen million, four hundred ninety-five thousand, nine hundred ninety-one".