21012453021 has 16 divisors (see below), whose sum is σ = 32046783104. Its totient is φ = 11996688384.

The previous prime is 21012452983. The next prime is 21012453029. The reversal of 21012453021 is 12035421012.

It is not a de Polignac number, because 21012453021 - 2⁷ = 21012452893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012453029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 409696 + ... + 458121.

It is an arithmetic number, because the mean of its divisors is an integer number (2002923944).

Almost surely, 2^21012453021 is an apocalyptic number.

21012453021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21012453021 is a deficient number, since it is larger than the sum of its proper divisors (11034330083).

21012453021 is a wasteful number, since it uses less digits than its factorization.

21012453021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868980.

The product of its (nonzero) digits is 480, while the sum is 21.

Adding to 21012453021 its reverse (12035421012), we get a palindrome (33047874033).

The spelling of 21012453021 in words is "twenty-one billion, twelve million, four hundred fifty-three thousand, twenty-one".