21201011999965 has 12 divisors (see below), whose sum is σ = 29594882057436. Its totient is φ = 14537836799808.

The previous prime is 21201011999933. The next prime is 21201011999969. The reversal of 21201011999965 is 56999911010212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 13476108844324 + 7724903155641 = 3670982^2 + 2779371^2 .

It is not a de Polignac number, because 21201011999965 - 2⁵ = 21201011999933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201011999969) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43267371184 + ... + 43267371673.

It is an arithmetic number, because the mean of its divisors is an integer number (2466240171453).

Almost surely, 2^{21201011999965} is an apocalyptic number.

It is an amenable number.

21201011999965 is a deficient number, since it is larger than the sum of its proper divisors (8393870057471).

21201011999965 is an equidigital number, since it uses as much as digits as its factorization.

21201011999965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86534742876 (or 86534742869 counting only the distinct ones).

The product of its (nonzero) digits is 787320, while the sum is 55.

The spelling of 21201011999965 in words is "twenty-one trillion, two hundred one billion, eleven million, nine hundred ninety-nine thousand, nine hundred sixty-five".