21501521023 has 8 divisors (see below), whose sum is σ = 21542336208. Its totient is φ = 21460731264.

The previous prime is 21501521003. The next prime is 21501521053. The reversal of 21501521023 is 32012510512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21501521023 - 2¹³ = 21501512831 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21501520985 and 21501521003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21501521003) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2723640 + ... + 2731522.

It is an arithmetic number, because the mean of its divisors is an integer number (2692792026).

Almost surely, 2^21501521023 is an apocalyptic number.

21501521023 is a deficient number, since it is larger than the sum of its proper divisors (40815185).

21501521023 is an equidigital number, since it uses as much as digits as its factorization.

21501521023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12713.

The product of its (nonzero) digits is 600, while the sum is 22.

The spelling of 21501521023 in words is "twenty-one billion, five hundred one million, five hundred twenty-one thousand, twenty-three".