21428305920 has 576 divisors, whose sum is σ = 87576733440. Its totient is φ = 4869586944.

The previous prime is 21428305909. The next prime is 21428305931. The reversal of 21428305920 is 2950382412.

It is a happy number.

21428305920 is a `hidden beast` number, since 2 + 14 + 28 + 30 + 592 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21428305909) and next prime (21428305931).

It is a tau number, because it is divible by the number of its divisors (576).

It is a super-2 number, since 2×21428305920² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123862954 + ... + 123863126.

It is an arithmetic number, because the mean of its divisors is an integer number (152042940).

Almost surely, 2^21428305920 is an apocalyptic number.

21428305920 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 21428305920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43788366720).

21428305920 is an abundant number, since it is smaller than the sum of its proper divisors (66148427520).

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

21428305920 is an frugal number, since it uses more digits than its factorization.

21428305920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21428305920 in words is "twenty-one billion, four hundred twenty-eight million, three hundred five thousand, nine hundred twenty".