21123012 has 24 divisors (see below), whose sum is σ = 49361536. Its totient is φ = 7030368.

The previous prime is 21122971. The next prime is 21123013. The reversal of 21123012 is 21032112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21123013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14133 + ... + 15555.

Almost surely, 2^21123012 is an apocalyptic number.

It is an amenable number.

21123012 is an abundant number, since it is smaller than the sum of its proper divisors (28238524).

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

21123012 is a wasteful number, since it uses less digits than its factorization.

21123012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2667 (or 2665 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21123012 is about 4595.9778067349. The cubic root of 21123012 is about 276.4300688503.

Adding to 21123012 its reverse (21032112), we get a palindrome (42155124).

The spelling of 21123012 in words is "twenty-one million, one hundred twenty-three thousand, twelve".