21541251593 has 4 divisors (see below), whose sum is σ = 22123447620. Its totient is φ = 20959055568.

The previous prime is 21541251583. The next prime is 21541251607. The reversal of 21541251593 is 39515214512.

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 19217722384 + 2323529209 = 138628^2 + 48203^2 .

It is a cyclic number.

It is not a de Polignac number, because 21541251593 - 2²⁸ = 21272816137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21541251553) 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, 291097958 + ... + 291098031.

It is an arithmetic number, because the mean of its divisors is an integer number (5530861905).

Almost surely, 2^21541251593 is an apocalyptic number.

It is an amenable number.

21541251593 is a deficient number, since it is larger than the sum of its proper divisors (582196027).

21541251593 is an equidigital number, since it uses as much as digits as its factorization.

21541251593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582196026.

The product of its digits is 54000, while the sum is 38.

The spelling of 21541251593 in words is "twenty-one billion, five hundred forty-one million, two hundred fifty-one thousand, five hundred ninety-three".