21572101 has 4 divisors (see below), whose sum is σ = 21925804. Its totient is φ = 21218400.

The previous prime is 21572077. The next prime is 21572119. The reversal of 21572101 is 10127512.

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 181476 + 21390625 = 426^2 + 4625^2 .

It is a cyclic number.

It is not a de Polignac number, because 21572101 - 2⁵ = 21572069 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 (21572141) 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, 176760 + ... + 176881.

It is an arithmetic number, because the mean of its divisors is an integer number (5481451).

Almost surely, 2^21572101 is an apocalyptic number.

It is an amenable number.

21572101 is a deficient number, since it is larger than the sum of its proper divisors (353703).

21572101 is an equidigital number, since it uses as much as digits as its factorization.

21572101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353702.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21572101 is about 4644.5775911271. The cubic root of 21572101 is about 278.3753749427.

Adding to 21572101 its reverse (10127512), we get a palindrome (31699613).

The spelling of 21572101 in words is "twenty-one million, five hundred seventy-two thousand, one hundred one".