19971961 has 9 divisors (see below), whose sum is σ = 20660493.
Its totient is φ = 19306080.
The previous prime is 19971953. The next prime is 19971979. The reversal of 19971961 is 16917991.
It is a happy number.
The square root of 19971961 is 4469.
It is a perfect power (a square), and thus also a powerful number.
It can be written as a sum of positive squares in 4 ways, for example, as 2499561 + 17472400 = 1581^2 + 4180^2
It is not a de Polignac number, because 19971961 - 23 = 19971953 is a prime.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (19971761) by changing a digit.
It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 183175 + ... + 183283.
Almost surely, 219971961 is an apocalyptic number.
19971961 is the 4469-th square number.
19971961 is the 2235-th centered octagonal number.
It is an amenable number.
19971961 is a deficient number, since it is larger than the sum of its proper divisors (688532).
19971961 is an frugal number, since it uses more digits than its factorization.
19971961 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 300 (or 150 counting only the distinct ones).
The product of its digits is 30618, while the sum is 43.
The cubic root of 19971961 is about 271.3148530753.
The spelling of 19971961 in words is "nineteen million, nine hundred seventy-one thousand, nine hundred sixty-one".