21123012132 has 36 divisors (see below), whose sum is σ = 53451350316. Its totient is φ = 7033478400.

The previous prime is 21123012121. The next prime is 21123012133. The reversal of 21123012132 is 23121032112.

It can be written as a sum of positive squares in 2 ways, for example, as 8849917476 + 12273094656 = 94074^2 + 110784^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21123012133) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 279369 + ... + 346832.

It is an arithmetic number, because the mean of its divisors is an integer number (1484759731).

Almost surely, 2^21123012132 is an apocalyptic number.

It is an amenable number.

21123012132 is an abundant number, since it is smaller than the sum of its proper divisors (32328338184).

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

21123012132 is a wasteful number, since it uses less digits than its factorization.

21123012132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627148 (or 627143 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21123012132 its reverse (23121032112), we get a palindrome (44244044244).

The spelling of 21123012132 in words is "twenty-one billion, one hundred twenty-three million, twelve thousand, one hundred thirty-two".