21421701840 has 640 divisors, whose sum is σ = 87007002624. Its totient is φ = 4230144000.

The previous prime is 21421701793. The next prime is 21421701841. The reversal of 21421701840 is 4810712412.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21421701798 and 21421701807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421701841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 34945374 + ... + 34945986.

Almost surely, 2^21421701840 is an apocalyptic number.

21421701840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21421701840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43503501312).

21421701840 is an abundant number, since it is smaller than the sum of its proper divisors (65585300784).

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

21421701840 is a wasteful number, since it uses less digits than its factorization.

21421701840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 739 (or 733 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The spelling of 21421701840 in words is "twenty-one billion, four hundred twenty-one million, seven hundred one thousand, eight hundred forty".