21021581745078 has 8 divisors (see below), whose sum is σ = 42043163490168. Its totient is φ = 7007193915024.

The previous prime is 21021581745013. The next prime is 21021581745083. The reversal of 21021581745078 is 87054718512012.

It is a sphenic number, since it is the product of 3 distinct primes.

21021581745078 is an admirable number.

It is a super-2 number, since 2×21021581745078² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21021581745078.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1751798478751 + ... + 1751798478762.

It is an arithmetic number, because the mean of its divisors is an integer number (5255395436271).

Almost surely, 2^{21021581745078} is an apocalyptic number.

21021581745078 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21021581745078 is a wasteful number, since it uses less digits than its factorization.

21021581745078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3503596957518.

The product of its (nonzero) digits is 1254400, while the sum is 51.

The spelling of 21021581745078 in words is "twenty-one trillion, twenty-one billion, five hundred eighty-one million, seven hundred forty-five thousand, seventy-eight".