21011512523 has 4 divisors (see below), whose sum is σ = 21012620448. Its totient is φ = 21010404600.

The previous prime is 21011512481. The next prime is 21011512567. The reversal of 21011512523 is 32521511012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21011512523 - 2⁸ = 21011512267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011572523) 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 3 ways as a sum of consecutive naturals, for example, 525011 + ... + 563612.

It is an arithmetic number, because the mean of its divisors is an integer number (5253155112).

Almost surely, 2^21011512523 is an apocalyptic number.

21011512523 is a deficient number, since it is larger than the sum of its proper divisors (1107925).

21011512523 is a wasteful number, since it uses less digits than its factorization.

21011512523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1107924.

The product of its (nonzero) digits is 600, while the sum is 23.

The spelling of 21011512523 in words is "twenty-one billion, eleven million, five hundred twelve thousand, five hundred twenty-three".