21021100000021 has 16 divisors (see below), whose sum is σ = 22997908447488. Its totient is φ = 19055262054400.

The previous prime is 21021099999983. The next prime is 21021100000037. The reversal of 21021100000021 is 12000000112012.

It is not a de Polignac number, because 21021100000021 - 2¹⁷ = 21021099868949 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021099999953 and 21021100000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021100000051) 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, 128332845 + ... + 128496541.

It is an arithmetic number, because the mean of its divisors is an integer number (1437369277968).

Almost surely, 2^{21021100000021} is an apocalyptic number.

It is an amenable number.

21021100000021 is a deficient number, since it is larger than the sum of its proper divisors (1976808447467).

21021100000021 is a wasteful number, since it uses less digits than its factorization.

21021100000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197132.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21021100000021 its reverse (12000000112012), we get a palindrome (33021100112033).

The spelling of 21021100000021 in words is "twenty-one trillion, twenty-one billion, one hundred million, twenty-one", and thus it is an aban number.