21152153021 has 4 divisors (see below), whose sum is σ = 22071811872. Its totient is φ = 20232494172.

The previous prime is 21152153017. The next prime is 21152153039. The reversal of 21152153021 is 12035125112.

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 not a de Polignac number, because 21152153021 - 2² = 21152153017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 919658827 = 21152153021 / (2 + 1 + 1 + 5 + 2 + 1 + 5 + 3 + 0 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152153051) 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, 459829391 + ... + 459829436.

It is an arithmetic number, because the mean of its divisors is an integer number (5517952968).

Almost surely, 2^21152153021 is an apocalyptic number.

It is an amenable number.

21152153021 is a deficient number, since it is larger than the sum of its proper divisors (919658851).

21152153021 is an equidigital number, since it uses as much as digits as its factorization.

21152153021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 919658850.

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

Adding to 21152153021 its reverse (12035125112), we get a palindrome (33187278133).

The spelling of 21152153021 in words is "twenty-one billion, one hundred fifty-two million, one hundred fifty-three thousand, twenty-one".