19778131 has 4 divisors (see below), whose sum is σ = 19909264. Its totient is φ = 19647000.

The previous prime is 19778119. The next prime is 19778149. The reversal of 19778131 is 13187791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13187791 = 251 ⋅52541.

It is a cyclic number.

It is not a de Polignac number, because 19778131 - 2⁹ = 19777619 is a prime.

It is a super-2 number, since 2×19778131² = 782348931706322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19778431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65340 + ... + 65641.

It is an arithmetic number, because the mean of its divisors is an integer number (4977316).

Almost surely, 2^19778131 is an apocalyptic number.

19778131 is a deficient number, since it is larger than the sum of its proper divisors (131133).

19778131 is a wasteful number, since it uses less digits than its factorization.

19778131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131132.

The product of its digits is 10584, while the sum is 37.

The square root of 19778131 is about 4447.2610672188. The cubic root of 19778131 is about 270.4342850902.

The spelling of 19778131 in words is "nineteen million, seven hundred seventy-eight thousand, one hundred thirty-one".