21350153021 has 4 divisors (see below), whose sum is σ = 21505993692. Its totient is φ = 21194312352.

The previous prime is 21350152987. The next prime is 21350153023. The reversal of 21350153021 is 12035105312.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5115825625 + 16234327396 = 71525^2 + 127414^2 .

It is a cyclic number.

It is not a de Polignac number, because 21350153021 - 2¹⁴ = 21350136637 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 (21350153023) 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, 77920130 + ... + 77920403.

It is an arithmetic number, because the mean of its divisors is an integer number (5376498423).

Almost surely, 2^21350153021 is an apocalyptic number.

It is an amenable number.

21350153021 is a deficient number, since it is larger than the sum of its proper divisors (155840671).

21350153021 is a wasteful number, since it uses less digits than its factorization.

21350153021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155840670.

The product of its (nonzero) digits is 900, while the sum is 23.

Adding to 21350153021 its reverse (12035105312), we get a palindrome (33385258333).

The spelling of 21350153021 in words is "twenty-one billion, three hundred fifty million, one hundred fifty-three thousand, twenty-one".