21076665456 has 320 divisors, whose sum is σ = 69238996992. Its totient is φ = 5366400000.

The previous prime is 21076665437. The next prime is 21076665461. The reversal of 21076665456 is 65456667012.

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 (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 48901561 + ... + 48901991.

Almost surely, 2^21076665456 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 21076665456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34619498496).

21076665456 is an abundant number, since it is smaller than the sum of its proper divisors (48162331536).

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

21076665456 is a wasteful number, since it uses less digits than its factorization.

21076665456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 686 counting only the distinct ones).

The product of its (nonzero) digits is 1814400, while the sum is 48.

The spelling of 21076665456 in words is "twenty-one billion, seventy-six million, six hundred sixty-five thousand, four hundred fifty-six".