21054781440 has 1536 divisors, whose sum is σ = 99632332800. Its totient is φ = 4087480320.

The previous prime is 21054781421. The next prime is 21054781499. The reversal of 21054781440 is 4418745012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (1536).

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

It is a junction number, because it is equal to n+sod(n) for n = 21054781395 and 21054781404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 489646059 + ... + 489646101.

It is an arithmetic number, because the mean of its divisors is an integer number (64864800).

Almost surely, 2^21054781440 is an apocalyptic number.

21054781440 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 21054781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49816166400).

21054781440 is an abundant number, since it is smaller than the sum of its proper divisors (78577551360).

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

21054781440 is a wasteful number, since it uses less digits than its factorization.

21054781440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120 (or 94 counting only the distinct ones).

The product of its (nonzero) digits is 35840, while the sum is 36.

The spelling of 21054781440 in words is "twenty-one billion, fifty-four million, seven hundred eighty-one thousand, four hundred forty".