21000020012021 has 16 divisors (see below), whose sum is σ = 22703211245760. Its totient is φ = 19356644545920.

The previous prime is 21000020012003. The next prime is 21000020012051. The reversal of 21000020012021 is 12021002000012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21000020012021 - 2²⁶ = 20999952903157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000020011993 and 21000020012011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000020012051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35295761 + ... + 35885801.

It is an arithmetic number, because the mean of its divisors is an integer number (1418950702860).

Almost surely, 2^{21000020012021} is an apocalyptic number.

It is an amenable number.

21000020012021 is a deficient number, since it is larger than the sum of its proper divisors (1703191233739).

21000020012021 is a wasteful number, since it uses less digits than its factorization.

21000020012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640724.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21000020012021 its reverse (12021002000012), we get a palindrome (33021022012033).

The spelling of 21000020012021 in words is "twenty-one trillion, twenty million, twelve thousand, twenty-one".