21152350451621 has 4 divisors (see below), whose sum is σ = 21152507047212. Its totient is φ = 21152193856032.

The previous prime is 21152350451527. The next prime is 21152350451641. The reversal of 21152350451621 is 12615405325112.

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 17042770067521 + 4109580384100 = 4128289^2 + 2027210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21152350451621 is a prime.

It is a super-2 number, since 2×21152350451621² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152350451641) 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, 78095006 + ... + 78365391.

It is an arithmetic number, because the mean of its divisors is an integer number (5288126761803).

Almost surely, 2^{21152350451621} is an apocalyptic number.

It is an amenable number.

21152350451621 is a deficient number, since it is larger than the sum of its proper divisors (156595591).

21152350451621 is a wasteful number, since it uses less digits than its factorization.

21152350451621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156595590.

The product of its (nonzero) digits is 72000, while the sum is 38.

Adding to 21152350451621 its reverse (12615405325112), we get a palindrome (33767755776733).

The spelling of 21152350451621 in words is "twenty-one trillion, one hundred fifty-two billion, three hundred fifty million, four hundred fifty-one thousand, six hundred twenty-one".