21858404020 has 12 divisors (see below), whose sum is σ = 45902648484. Its totient is φ = 8743361600.

The previous prime is 21858403999. The next prime is 21858404047. The reversal of 21858404020 is 2040485812.

It can be written as a sum of positive squares in 2 ways, for example, as 14458619536 + 7399784484 = 120244^2 + 86022^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 546460081 + ... + 546460120.

It is an arithmetic number, because the mean of its divisors is an integer number (3825220707).

Almost surely, 2^21858404020 is an apocalyptic number.

21858404020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21858404020 is an abundant number, since it is smaller than the sum of its proper divisors (24044244464).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21858404020 is a wasteful number, since it uses less digits than its factorization.

21858404020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092920210 (or 1092920208 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 34.

Adding to 21858404020 its reverse (2040485812), we get a palindrome (23898889832).

The spelling of 21858404020 in words is "twenty-one billion, eight hundred fifty-eight million, four hundred four thousand, twenty".