999999999961 has 2 divisors, whose sum is σ = 999999999962.
Its totient is φ = 999999999960.
The previous prime is 999999999959. The next prime is 999999999989. The reversal of 999999999961 is 169999999999.
It is a happy number.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 793106019225 + 206893980736 = 890565^2 + 454856^2
It is a cyclic number.
It is not a de Polignac number, because 999999999961 - 21 = 999999999959 is a prime.
Together with 999999999959, it forms a pair of twin primes.
It is a nialpdrome in base 10.
It is not a weakly prime, because it can be changed into another prime (999999999161) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999999980 + 499999999981.
It is an arithmetic number, because the mean of its divisors is an integer number (499999999981).
Almost surely, 2999999999961 is an apocalyptic number.
It is an amenable number.
999999999961 is a deficient number, since it is larger than the sum of its proper divisors (1).
999999999961 is an equidigital number, since it uses as much as digits as its factorization.
999999999961 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 20920706406, while the sum is 97.
The spelling of 999999999961 in words is "nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred sixty-one".