1221021021 has 8 divisors (see below), whose sum is σ = 1776030624. Its totient is φ = 740012720.

The previous prime is 1221021007. The next prime is 1221021059. The reversal of 1221021021 is 1201201221.

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 1221021021 - 2⁷ = 1221020893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221020988 and 1221021006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221021721) 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, 18500286 + ... + 18500351.

It is an arithmetic number, because the mean of its divisors is an integer number (222003828).

Almost surely, 2^1221021021 is an apocalyptic number.

1221021021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221021021 is a deficient number, since it is larger than the sum of its proper divisors (555009603).

1221021021 is a wasteful number, since it uses less digits than its factorization.

1221021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37000651.

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

The square root of 1221021021 is about 34943.1112095074. Note that the first 3 decimals coincide. The cubic root of 1221021021 is about 1068.8277320844.

Adding to 1221021021 its reverse (1201201221), we get a palindrome (2422222242).

It can be divided in two parts, 12 and 21021021, that multiplied together give a palindrome (252252252).

The spelling of 1221021021 in words is "one billion, two hundred twenty-one million, twenty-one thousand, twenty-one".