21121222100021 has 16 divisors (see below), whose sum is σ = 23166983923200. Its totient is φ = 19166626714368.

The previous prime is 21121222099973. The next prime is 21121222100023. The reversal of 21121222100021 is 12000122212112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121222100021 is a prime.

It is a super-2 number, since 2×21121222100021² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121222100023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29438465 + ... + 30147398.

It is an arithmetic number, because the mean of its divisors is an integer number (1447936495200).

Almost surely, 2^{21121222100021} is an apocalyptic number.

It is an amenable number.

21121222100021 is a deficient number, since it is larger than the sum of its proper divisors (2045761823179).

21121222100021 is a wasteful number, since it uses less digits than its factorization.

21121222100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59586628.

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

Adding to 21121222100021 its reverse (12000122212112), we get a palindrome (33121344312133).

The spelling of 21121222100021 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty-two million, one hundred thousand, twenty-one".