20101010921 has 4 divisors (see below), whose sum is σ = 20480275332. Its totient is φ = 19721746512.

The previous prime is 20101010873. The next prime is 20101010927. The reversal of 20101010921 is 12901010102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12901010102 = 2 ⋅6450505051.

It can be written as a sum of positive squares in 2 ways, for example, as 16756008025 + 3345002896 = 129445^2 + 57836^2 .

It is a cyclic number.

It is not a de Polignac number, because 20101010921 - 2⁶ = 20101010857 is a prime.

It is a super-2 number, since 2×20101010921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20101010921.

It is not an unprimeable number, because it can be changed into a prime (20101010927) 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, 189632126 + ... + 189632231.

It is an arithmetic number, because the mean of its divisors is an integer number (5120068833).

Almost surely, 2^20101010921 is an apocalyptic number.

It is an amenable number.

20101010921 is a deficient number, since it is larger than the sum of its proper divisors (379264411).

20101010921 is an equidigital number, since it uses as much as digits as its factorization.

20101010921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379264410.

The product of its (nonzero) digits is 36, while the sum is 17.

The spelling of 20101010921 in words is "twenty billion, one hundred one million, ten thousand, nine hundred twenty-one".