21101021001 has 12 divisors (see below), whose sum is σ = 30483697140. Its totient is φ = 14065296000.

The previous prime is 21101020991. The next prime is 21101021023. The reversal of 21101021001 is 10012010112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8204011776 + 12897009225 = 90576^2 + 113565^2 .

It is not a de Polignac number, because 21101021001 - 2⁷ = 21101020873 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21101028001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 104436 + ... + 230453.

It is an arithmetic number, because the mean of its divisors is an integer number (2540308095).

Almost surely, 2^21101021001 is an apocalyptic number.

It is an amenable number.

21101021001 is a deficient number, since it is larger than the sum of its proper divisors (9382676139).

21101021001 is a wasteful number, since it uses less digits than its factorization.

21101021001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341896 (or 341893 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21101021001 its reverse (10012010112), we get a palindrome (31113031113).

The spelling of 21101021001 in words is "twenty-one billion, one hundred one million, twenty-one thousand, one".