20821955911 has 8 divisors (see below), whose sum is σ = 20958219680. Its totient is φ = 20685738528.

The previous prime is 20821955899. The next prime is 20821955939. The reversal of 20821955911 is 11955912802.

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 20821955911 - 2¹³ = 20821947719 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20821955981) 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, 1770910 + ... + 1782628.

It is an arithmetic number, because the mean of its divisors is an integer number (2619777460).

Almost surely, 2^20821955911 is an apocalyptic number.

20821955911 is a deficient number, since it is larger than the sum of its proper divisors (136263769).

20821955911 is a wasteful number, since it uses less digits than its factorization.

20821955911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23193.

The product of its (nonzero) digits is 64800, while the sum is 43.

The spelling of 20821955911 in words is "twenty billion, eight hundred twenty-one million, nine hundred fifty-five thousand, nine hundred eleven".