21101211001 has 4 divisors (see below), whose sum is σ = 22724381092. Its totient is φ = 19478040912.

The previous prime is 21101210959. The next prime is 21101211059. The reversal of 21101211001 is 10011210112.

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 13788395776 + 7312815225 = 117424^2 + 85515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101211001 - 2⁹ = 21101210489 is a prime.

It is a super-2 number, since 2×21101211001² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101211071) 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, 811585026 + ... + 811585051.

It is an arithmetic number, because the mean of its divisors is an integer number (5681095273).

Almost surely, 2^21101211001 is an apocalyptic number.

It is an amenable number.

21101211001 is a deficient number, since it is larger than the sum of its proper divisors (1623170091).

21101211001 is a wasteful number, since it uses less digits than its factorization.

21101211001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1623170090.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21101211001 its reverse (10011210112), we get a palindrome (31112421113).

The spelling of 21101211001 in words is "twenty-one billion, one hundred one million, two hundred eleven thousand, one".