21021221121011 has 4 divisors (see below), whose sum is σ = 22257763539912. Its totient is φ = 19784678702112.

The previous prime is 21021221120987. The next prime is 21021221121083. The reversal of 21021221121011 is 11012112212012.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21021221121011 - 2³⁸ = 20746343214067 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1236542418883 = 21021221121011 / (2 + 1 + 0 + 2 + 1 + 2 + 2 + 1 + 1 + 2 + 1 + 0 + 1 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021221121211) 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, 618271209425 + ... + 618271209458.

It is an arithmetic number, because the mean of its divisors is an integer number (5564440884978).

Almost surely, 2^{21021221121011} is an apocalyptic number.

21021221121011 is a deficient number, since it is larger than the sum of its proper divisors (1236542418901).

21021221121011 is a wasteful number, since it uses less digits than its factorization.

21021221121011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1236542418900.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21021221121011 its reverse (11012112212012), we get a palindrome (32033333333023).

The spelling of 21021221121011 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, one hundred twenty-one thousand, eleven".