21111221012121 has 64 divisors (see below), whose sum is σ = 33361993324800. Its totient is φ = 13171804918272.

The previous prime is 21111221012107. The next prime is 21111221012129. The reversal of 21111221012121 is 12121012211112.

It is a happy number.

21111221012121 is a `hidden beast` number, since 211 + 112 + 210 + 12 + 121 = 666.

It is not a de Polignac number, because 21111221012121 - 2²¹ = 21111218914969 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111221012094 and 21111221012103.

It is not an unprimeable number, because it can be changed into a prime (21111221012129) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 379861 + ... + 6508973.

It is an arithmetic number, because the mean of its divisors is an integer number (521281145700).

Almost surely, 2^{21111221012121} is an apocalyptic number.

It is an amenable number.

21111221012121 is a deficient number, since it is larger than the sum of its proper divisors (12250772312679).

21111221012121 is a wasteful number, since it uses less digits than its factorization.

21111221012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6129287 (or 6129281 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21111221012121 its reverse (12121012211112), we get a palindrome (33232233223233).

The spelling of 21111221012121 in words is "twenty-one trillion, one hundred eleven billion, two hundred twenty-one million, twelve thousand, one hundred twenty-one".