21101001001 has 8 divisors (see below), whose sum is σ = 22887169704. Its totient is φ = 19375380480.

The previous prime is 21101000993. The next prime is 21101001013. The reversal of 21101001001 is 10010010112.

It can be written as a sum of positive squares in 4 ways, for example, as 2299106601 + 18801894400 = 47949^2 + 137120^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21101001001 - 2³ = 21101000993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101001401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15136320 + ... + 15137713.

It is an arithmetic number, because the mean of its divisors is an integer number (2860896213).

Almost surely, 2^21101001001 is an apocalyptic number.

It is an amenable number.

21101001001 is a deficient number, since it is larger than the sum of its proper divisors (1786168703).

21101001001 is a wasteful number, since it uses less digits than its factorization.

21101001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30274091.

The product of its (nonzero) digits is 2, while the sum is 7.

Adding to 21101001001 its reverse (10010010112), we get a palindrome (31111011113).

The spelling of 21101001001 in words is "twenty-one billion, one hundred one million, one thousand, one".