21161161700621 has 4 divisors (see below), whose sum is σ = 21161361528732. Its totient is φ = 21160961872512.

The previous prime is 21161161700587. The next prime is 21161161700677. The reversal of 21161161700621 is 12600716116112.

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 9511432251721 + 11649729448900 = 3084061^2 + 3413170^2 .

It is a cyclic number.

It is not a de Polignac number, because 21161161700621 - 2²⁶ = 21161094591757 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161161700681) 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, 99755126 + ... + 99967031.

It is an arithmetic number, because the mean of its divisors is an integer number (5290340382183).

Almost surely, 2^{21161161700621} is an apocalyptic number.

It is an amenable number.

21161161700621 is a deficient number, since it is larger than the sum of its proper divisors (199828111).

21161161700621 is a wasteful number, since it uses less digits than its factorization.

21161161700621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199828110.

The product of its (nonzero) digits is 6048, while the sum is 35.

Adding to 21161161700621 its reverse (12600716116112), we get a palindrome (33761877816733).

The spelling of 21161161700621 in words is "twenty-one trillion, one hundred sixty-one billion, one hundred sixty-one million, seven hundred thousand, six hundred twenty-one".