21021002121 has 16 divisors (see below), whose sum is σ = 32082787328. Its totient is φ = 11992957200.

The previous prime is 21021002111. The next prime is 21021002131. The reversal of 21021002121 is 12120012012.

It is an interprime number because it is at equal distance from previous prime (21021002111) and next prime (21021002131).

It is not a de Polignac number, because 21021002121 - 2¹⁰ = 21021001097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021002097 and 21021002106.

It is not an unprimeable number, because it can be changed into a prime (21021002111) 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, 779935 + ... + 806436.

It is an arithmetic number, because the mean of its divisors is an integer number (2005174208).

Almost surely, 2^21021002121 is an apocalyptic number.

21021002121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21021002121 is a deficient number, since it is larger than the sum of its proper divisors (11061785207).

21021002121 is a wasteful number, since it uses less digits than its factorization.

21021002121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1587012.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21021002121 its reverse (12120012012), we get a palindrome (33141014133).

The spelling of 21021002121 in words is "twenty-one billion, twenty-one million, two thousand, one hundred twenty-one".