21855454420 has 12 divisors (see below), whose sum is σ = 45896454324. Its totient is φ = 8742181760.

The previous prime is 21855454399. The next prime is 21855454457. The reversal of 21855454420 is 2445455812.

It can be written as a sum of positive squares in 2 ways, for example, as 11086826436 + 10768627984 = 105294^2 + 103772^2 .

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, 546386341 + ... + 546386380.

It is an arithmetic number, because the mean of its divisors is an integer number (3824704527).

Almost surely, 2^21855454420 is an apocalyptic number.

21855454420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21855454420 is an abundant number, since it is smaller than the sum of its proper divisors (24040999904).

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

21855454420 is a wasteful number, since it uses less digits than its factorization.

21855454420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092772730 (or 1092772728 counting only the distinct ones).

The product of its (nonzero) digits is 256000, while the sum is 40.

The spelling of 21855454420 in words is "twenty-one billion, eight hundred fifty-five million, four hundred fifty-four thousand, four hundred twenty".