21408887420 has 24 divisors (see below), whose sum is σ = 45378842544. Its totient is φ = 8483520896.

The previous prime is 21408887377. The next prime is 21408887443. The reversal of 21408887420 is 2478880412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4999937 + ... + 5004216.

It is an arithmetic number, because the mean of its divisors is an integer number (1890785106).

Almost surely, 2^21408887420 is an apocalyptic number.

21408887420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21408887420 is an abundant number, since it is smaller than the sum of its proper divisors (23969955124).

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

21408887420 is a wasteful number, since it uses less digits than its factorization.

21408887420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10004269 (or 10004267 counting only the distinct ones).

The product of its (nonzero) digits is 229376, while the sum is 44.

The spelling of 21408887420 in words is "twenty-one billion, four hundred eight million, eight hundred eighty-seven thousand, four hundred twenty".