20138804921 has 8 divisors (see below), whose sum is σ = 20953675080. Its totient is φ = 19331963392.

The previous prime is 20138804867. The next prime is 20138804977. The reversal of 20138804921 is 12940883102.

It can be written as a sum of positive squares in 4 ways, for example, as 9945075625 + 10193729296 = 99725^2 + 100964^2 .

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 20138804921 - 2³⁰ = 19065063097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20138804821) 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, 2002040 + ... + 2012073.

It is an arithmetic number, because the mean of its divisors is an integer number (2619209385).

Almost surely, 2^20138804921 is an apocalyptic number.

It is an amenable number.

20138804921 is a deficient number, since it is larger than the sum of its proper divisors (814870159).

20138804921 is a wasteful number, since it uses less digits than its factorization.

20138804921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4014315.

The product of its (nonzero) digits is 27648, while the sum is 38.

The spelling of 20138804921 in words is "twenty billion, one hundred thirty-eight million, eight hundred four thousand, nine hundred twenty-one".