21335370921 has 20 divisors (see below), whose sum is σ = 33548798800. Its totient is φ = 13474970136.

The previous prime is 21335370913. The next prime is 21335370989. The reversal of 21335370921 is 12907353312.

It is a happy number.

21335370921 is a `hidden beast` number, since 2 + 1 + 33 + 537 + 0 + 92 + 1 = 666.

It is not a de Polignac number, because 21335370921 - 2³ = 21335370913 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21335370911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6930031 + ... + 6933108.

It is an arithmetic number, because the mean of its divisors is an integer number (1677439940).

Almost surely, 2^21335370921 is an apocalyptic number.

It is an amenable number.

21335370921 is a deficient number, since it is larger than the sum of its proper divisors (12213427879).

21335370921 is a wasteful number, since it uses less digits than its factorization.

21335370921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13863170 (or 13863161 counting only the distinct ones).

The product of its (nonzero) digits is 34020, while the sum is 36.

The spelling of 21335370921 in words is "twenty-one billion, three hundred thirty-five million, three hundred seventy thousand, nine hundred twenty-one".