21451017042 has 144 divisors (see below), whose sum is σ = 58686630912. Its totient is φ = 5612483520.

The previous prime is 21451016987. The next prime is 21451017053. The reversal of 21451017042 is 24071015412.

21451017042 is a `hidden beast` number, since 2 + 1 + 451 + 0 + 170 + 42 = 666.

It is a super-2 number, since 2×21451017042² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21451016997 and 21451017015.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1448817 + ... + 1463547.

It is an arithmetic number, because the mean of its divisors is an integer number (407546048).

Almost surely, 2^21451017042 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21451017042, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29343315456).

21451017042 is an abundant number, since it is smaller than the sum of its proper divisors (37235613870).

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

21451017042 is a wasteful number, since it uses less digits than its factorization.

21451017042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14893 (or 14883 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The spelling of 21451017042 in words is "twenty-one billion, four hundred fifty-one million, seventeen thousand, forty-two".