1221211220021 has 8 divisors (see below), whose sum is σ = 1315168667904. Its totient is φ = 1127256361200.

The previous prime is 1221211219997. The next prime is 1221211220029. The reversal of 1221211220021 is 1200221121221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221211220021 - 2⁶ = 1221211219957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211220029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 394496 + ... + 1611846.

It is an arithmetic number, because the mean of its divisors is an integer number (164396083488).

Almost surely, 2^{1221211220021} is an apocalyptic number.

It is an amenable number.

1221211220021 is a deficient number, since it is larger than the sum of its proper divisors (93957447883).

1221211220021 is a wasteful number, since it uses less digits than its factorization.

1221211220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1294531.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 1221211220021 its reverse (1200221121221), we get a palindrome (2421432341242).

The spelling of 1221211220021 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, two hundred twenty thousand, twenty-one".