1221012110021 has 4 divisors (see below), whose sum is σ = 1332013210944. Its totient is φ = 1110011009100.

The previous prime is 1221012109979. The next prime is 1221012110023. The reversal of 1221012110021 is 1200112101221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221012110021 - 2⁶ = 1221012109957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221012109978 and 1221012110005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221012110023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55500550445 + ... + 55500550466.

It is an arithmetic number, because the mean of its divisors is an integer number (333003302736).

Almost surely, 2^{1221012110021} is an apocalyptic number.

1221012110021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221012110021 is a deficient number, since it is larger than the sum of its proper divisors (111001100923).

1221012110021 is a wasteful number, since it uses less digits than its factorization.

1221012110021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111001100922.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 1221012110021 its reverse (1200112101221), we get a palindrome (2421124211242).

The spelling of 1221012110021 in words is "one trillion, two hundred twenty-one billion, twelve million, one hundred ten thousand, twenty-one".