21020120121 has 144 divisors (see below), whose sum is σ = 39378554880. Its totient is φ = 9748252800.

The previous prime is 21020120111. The next prime is 21020120131. The reversal of 21020120121 is 12102102012.

It is an interprime number because it is at equal distance from previous prime (21020120111) and next prime (21020120131).

It is not a de Polignac number, because 21020120121 - 2⁶ = 21020120057 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020120097 and 21020120106.

It is not an unprimeable number, because it can be changed into a prime (21020120111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 13311510 + ... + 13313088.

Almost surely, 2^21020120121 is an apocalyptic number.

21020120121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21020120121 is a deficient number, since it is larger than the sum of its proper divisors (18358434759).

21020120121 is a wasteful number, since it uses less digits than its factorization.

21020120121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1668 (or 1644 counting only the distinct ones).

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

Adding to 21020120121 its reverse (12102102012), we get a palindrome (33122222133).

It can be divided in two parts, 21020 and 120121, that added together give a palindrome (141141).

The spelling of 21020120121 in words is "twenty-one billion, twenty million, one hundred twenty thousand, one hundred twenty-one".