19978955 has 4 divisors (see below), whose sum is σ = 23974752. Its totient is φ = 15983160.

The previous prime is 19978949. The next prime is 19978967. The reversal of 19978955 is 55987991.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 19978955 - 2⁴ = 19978939 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19978897 and 19978906.

It is an unprimeable number.

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, 1997891 + ... + 1997900.

It is an arithmetic number, because the mean of its divisors is an integer number (5993688).

Almost surely, 2^19978955 is an apocalyptic number.

19978955 is a deficient number, since it is larger than the sum of its proper divisors (3995797).

19978955 is an equidigital number, since it uses as much as digits as its factorization.

19978955 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3995796.

The product of its digits is 1020600, while the sum is 53.

The square root of 19978955 is about 4469.7824331840. The cubic root of 19978955 is about 271.3465200478.

The spelling of 19978955 in words is "nineteen million, nine hundred seventy-eight thousand, nine hundred fifty-five".