21150351521 has 12 divisors (see below), whose sum is σ = 23129227260. Its totient is φ = 19330084800.

The previous prime is 21150351487. The next prime is 21150351571. The reversal of 21150351521 is 12515305112.

It can be written as a sum of positive squares in 6 ways, for example, as 536570896 + 20613780625 = 23164^2 + 143575^2 .

It is not a de Polignac number, because 21150351521 - 2¹⁰ = 21150350497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21150351571) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 602486 + ... + 636623.

It is an arithmetic number, because the mean of its divisors is an integer number (1927435605).

Almost surely, 2^21150351521 is an apocalyptic number.

It is an amenable number.

21150351521 is a deficient number, since it is larger than the sum of its proper divisors (1978875739).

21150351521 is a wasteful number, since it uses less digits than its factorization.

21150351521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1239236 (or 1239223 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 26.

Adding to 21150351521 its reverse (12515305112), we get a palindrome (33665656633).

The spelling of 21150351521 in words is "twenty-one billion, one hundred fifty million, three hundred fifty-one thousand, five hundred twenty-one".