20173621821 has 16 divisors (see below), whose sum is σ = 26985625920. Its totient is φ = 13405392000.

The previous prime is 20173621807. The next prime is 20173621841. The reversal of 20173621821 is 12812637102.

It is not a de Polignac number, because 20173621821 - 2⁵ = 20173621789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20173621841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2514865 + ... + 2522873.

It is an arithmetic number, because the mean of its divisors is an integer number (1686601620).

Almost surely, 2^20173621821 is an apocalyptic number.

It is an amenable number.

20173621821 is a deficient number, since it is larger than the sum of its proper divisors (6812004099).

20173621821 is a wasteful number, since it uses less digits than its factorization.

20173621821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10636.

The product of its (nonzero) digits is 8064, while the sum is 33.

The spelling of 20173621821 in words is "twenty billion, one hundred seventy-three million, six hundred twenty-one thousand, eight hundred twenty-one".