21400477920 has 288 divisors, whose sum is σ = 74161694880. Its totient is φ = 5618995200.

The previous prime is 21400477913. The next prime is 21400478017. The reversal of 21400477920 is 2977400412.

It is a tau number, because it is divible by the number of its divisors (288).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39123087 + ... + 39123633.

It is an arithmetic number, because the mean of its divisors is an integer number (257505885).

Almost surely, 2^21400477920 is an apocalyptic number.

21400477920 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 21400477920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37080847440).

21400477920 is an abundant number, since it is smaller than the sum of its proper divisors (52761216960).

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

21400477920 is a wasteful number, since it uses less digits than its factorization.

21400477920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 938 (or 927 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 36.

The spelling of 21400477920 in words is "twenty-one billion, four hundred million, four hundred seventy-seven thousand, nine hundred twenty".