20409624121 has 4 divisors (see below), whose sum is σ = 20409923044. Its totient is φ = 20409325200.

The previous prime is 20409624119. The next prime is 20409624127. The reversal of 20409624121 is 12142690402.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15291795600 + 5117828521 = 123660^2 + 71539^2 .

It is a cyclic number.

It is not a de Polignac number, because 20409624121 - 2¹ = 20409624119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20409624127) 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, 8851 + ... + 202231.

It is an arithmetic number, because the mean of its divisors is an integer number (5102480761).

Almost surely, 2^20409624121 is an apocalyptic number.

It is an amenable number.

20409624121 is a deficient number, since it is larger than the sum of its proper divisors (298923).

20409624121 is a wasteful number, since it uses less digits than its factorization.

20409624121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298922.

The product of its (nonzero) digits is 6912, while the sum is 31.

The spelling of 20409624121 in words is "twenty billion, four hundred nine million, six hundred twenty-four thousand, one hundred twenty-one".