21611167606421 has 4 divisors (see below), whose sum is σ = 21611435958732. Its totient is φ = 21610899254112.

The previous prime is 21611167606411. The next prime is 21611167606429. The reversal of 21611167606421 is 12460676111612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6995945650225 + 14615221956196 = 2644985^2 + 3822986^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611167606421 - 2¹⁰ = 21611167605397 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 (21611167606429) 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, 134055320 + ... + 134216433.

It is an arithmetic number, because the mean of its divisors is an integer number (5402858989683).

Almost surely, 2^{21611167606421} is an apocalyptic number.

It is an amenable number.

21611167606421 is a deficient number, since it is larger than the sum of its proper divisors (268352311).

21611167606421 is an equidigital number, since it uses as much as digits as its factorization.

21611167606421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268352310.

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 21611167606421 in words is "twenty-one trillion, six hundred eleven billion, one hundred sixty-seven million, six hundred six thousand, four hundred twenty-one".