21201011999956 has 24 divisors (see below), whose sum is σ = 37260906189696. Its totient is φ = 10555128929280.

The previous prime is 21201011999933. The next prime is 21201011999969. The reversal of 21201011999956 is 65999911010212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21201011999897 and 21201011999906.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10324306 + ... + 12206281.

It is an arithmetic number, because the mean of its divisors is an integer number (1552537757904).

Almost surely, 2^{21201011999956} is an apocalyptic number.

It is an amenable number.

21201011999956 is a deficient number, since it is larger than the sum of its proper divisors (16059894189740).

21201011999956 is a wasteful number, since it uses less digits than its factorization.

21201011999956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22531599 (or 22531597 counting only the distinct ones).

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

The spelling of 21201011999956 in words is "twenty-one trillion, two hundred one billion, eleven million, nine hundred ninety-nine thousand, nine hundred fifty-six".