21278645472 has 192 divisors, whose sum is σ = 65840947200. Its totient is φ = 5891612160.

The previous prime is 21278645467. The next prime is 21278645501. The reversal of 21278645472 is 27454687212.

It is a super-2 number, since 2×21278645472² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2811229 + ... + 2818787.

It is an arithmetic number, because the mean of its divisors is an integer number (342921600).

Almost surely, 2^21278645472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21278645472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32920473600).

21278645472 is an abundant number, since it is smaller than the sum of its proper divisors (44562301728).

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

21278645472 is a wasteful number, since it uses less digits than its factorization.

21278645472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7709 (or 7701 counting only the distinct ones).

The product of its digits is 1505280, while the sum is 48.

The spelling of 21278645472 in words is "twenty-one billion, two hundred seventy-eight million, six hundred forty-five thousand, four hundred seventy-two".