21215543201 has 4 divisors (see below), whose sum is σ = 21240299652. Its totient is φ = 21190786752.

The previous prime is 21215543179. The next prime is 21215543231. The reversal of 21215543201 is 10234551212.

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 20072088976 + 1143454225 = 141676^2 + 33815^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215543201 - 2¹⁴ = 21215526817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21215543231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12376940 + ... + 12378653.

It is an arithmetic number, because the mean of its divisors is an integer number (5310074913).

Almost surely, 2^21215543201 is an apocalyptic number.

It is an amenable number.

21215543201 is a deficient number, since it is larger than the sum of its proper divisors (24756451).

21215543201 is an equidigital number, since it uses as much as digits as its factorization.

21215543201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24756450.

The product of its (nonzero) digits is 2400, while the sum is 26.

The spelling of 21215543201 in words is "twenty-one billion, two hundred fifteen million, five hundred forty-three thousand, two hundred one".