21152206421021 has 16 divisors (see below), whose sum is σ = 23983634653440. Its totient is φ = 18493291103040.

The previous prime is 21152206421011. The next prime is 21152206421023. The reversal of 21152206421021 is 12012460225112.

It is not a de Polignac number, because 21152206421021 - 2⁶ = 21152206420957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152206421023) 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, 8593205 + ... + 10777178.

It is an arithmetic number, because the mean of its divisors is an integer number (1498977165840).

Almost surely, 2^{21152206421021} is an apocalyptic number.

It is an amenable number.

21152206421021 is a deficient number, since it is larger than the sum of its proper divisors (2831428232419).

21152206421021 is a wasteful number, since it uses less digits than its factorization.

21152206421021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19374836.

The product of its (nonzero) digits is 3840, while the sum is 29.

Adding to 21152206421021 its reverse (12012460225112), we get a palindrome (33164666646133).

The spelling of 21152206421021 in words is "twenty-one trillion, one hundred fifty-two billion, two hundred six million, four hundred twenty-one thousand, twenty-one".