21123012101 has 4 divisors (see below), whose sum is σ = 22234749600. Its totient is φ = 20011274604.

The previous prime is 21123012049. The next prime is 21123012109. The reversal of 21123012101 is 10121032112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123012101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123012109) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 555868721 + ... + 555868758.

It is an arithmetic number, because the mean of its divisors is an integer number (5558687400).

Almost surely, 2^21123012101 is an apocalyptic number.

It is an amenable number.

21123012101 is a deficient number, since it is larger than the sum of its proper divisors (1111737499).

21123012101 is a wasteful number, since it uses less digits than its factorization.

21123012101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1111737498.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21123012101 its reverse (10121032112), we get a palindrome (31244044213).

The spelling of 21123012101 in words is "twenty-one billion, one hundred twenty-three million, twelve thousand, one hundred one".