21278051712 has 96 divisors (see below), whose sum is σ = 61261200000. Its totient is φ = 7089048576.

The previous prime is 21278051689. The next prime is 21278051719. The reversal of 21278051712 is 21715087212.

21278051712 is a `hidden beast` number, since 2 + 127 + 8 + 0 + 517 + 12 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×21278051712² (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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21278051719) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3163489 + ... + 3170207.

It is an arithmetic number, because the mean of its divisors is an integer number (638137500).

Almost surely, 2^21278051712 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 21278051712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30630600000).

21278051712 is an abundant number, since it is smaller than the sum of its proper divisors (39983148288).

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

21278051712 is a wasteful number, since it uses less digits than its factorization.

21278051712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9488 (or 9473 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 36.

The spelling of 21278051712 in words is "twenty-one billion, two hundred seventy-eight million, fifty-one thousand, seven hundred twelve".