21012423016 has 24 divisors (see below), whose sum is σ = 42662059830. Its totient is φ = 9698040768.

The previous prime is 21012423013. The next prime is 21012423041. The reversal of 21012423016 is 61032421012.

It can be written as a sum of positive squares in 3 ways, for example, as 15115718916 + 5896704100 = 122946^2 + 76790^2 .

It is not an unprimeable number, because it can be changed into a prime (21012423013) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 7769515 + ... + 7772218.

Almost surely, 2^21012423016 is an apocalyptic number.

21012423016 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21012423016 is an abundant number, since it is smaller than the sum of its proper divisors (21649636814).

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

21012423016 is a wasteful number, since it uses less digits than its factorization.

21012423016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15541765 (or 15541748 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

Adding to 21012423016 its reverse (61032421012), we get a palindrome (82044844028).

The spelling of 21012423016 in words is "twenty-one billion, twelve million, four hundred twenty-three thousand, sixteen".