21057172201 has 4 divisors (see below), whose sum is σ = 22676954692. Its totient is φ = 19437389712.

The previous prime is 21057172183. The next prime is 21057172271. The reversal of 21057172201 is 10227175012.

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 8041784976 + 13015387225 = 89676^2 + 114085^2 .

It is not a de Polignac number, because 21057172201 - 2³³ = 12467237609 is a prime.

It is a super-2 number, since 2×21057172201² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21057172201.

It is not an unprimeable number, because it can be changed into a prime (21057172271) 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, 809891226 + ... + 809891251.

It is an arithmetic number, because the mean of its divisors is an integer number (5669238673).

Almost surely, 2^21057172201 is an apocalyptic number.

It is an amenable number.

21057172201 is a deficient number, since it is larger than the sum of its proper divisors (1619782491).

21057172201 is a wasteful number, since it uses less digits than its factorization.

21057172201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1619782490.

The product of its (nonzero) digits is 1960, while the sum is 28.

The spelling of 21057172201 in words is "twenty-one billion, fifty-seven million, one hundred seventy-two thousand, two hundred one".