19997649 has 48 divisors (see below), whose sum is σ = 35473152.
Its totient is φ = 10606464.
The previous prime is 19997641. The next prime is 19997657. The reversal of 19997649 is 94679991.
It is an interprime number because it is at equal distance from previous prime (19997641) and next prime (19997657).
It is not a de Polignac number, because 19997649 - 23 = 19997641 is a prime.
It is a Curzon number.
It is a junction number, because it is equal to n+sod(n) for n = 19997595 and 19997604.
It is not an unprimeable number, because it can be changed into a prime (19997641) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 53427 + ... + 53799.
It is an arithmetic number, because the mean of its divisors is an integer number (739024).
Almost surely, 219997649 is an apocalyptic number.
It is an amenable number.
19997649 is a deficient number, since it is larger than the sum of its proper divisors (15475503).
19997649 is a wasteful number, since it uses less digits than its factorization.
19997649 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 446 (or 443 counting only the distinct ones).
The product of its digits is 1102248, while the sum is 54.
The square root of 19997649 is about 4471.8730974839.
The cubic root of 19997649 is about 271.4311252497.
The spelling of 19997649 in words is "nineteen million, nine hundred ninety-seven thousand, six hundred forty-nine".