21213231541 has 4 divisors (see below), whose sum is σ = 21213870732. Its totient is φ = 21212592352.

The previous prime is 21213231517. The next prime is 21213231553. The reversal of 21213231541 is 14513231212.

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 6864785316 + 14348446225 = 82854^2 + 119785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213231541 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 (21213231041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266920 + ... + 337153.

It is an arithmetic number, because the mean of its divisors is an integer number (5303467683).

Almost surely, 2^21213231541 is an apocalyptic number.

It is an amenable number.

21213231541 is a deficient number, since it is larger than the sum of its proper divisors (639191).

21213231541 is an equidigital number, since it uses as much as digits as its factorization.

21213231541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639190.

The product of its digits is 1440, while the sum is 25.

Adding to 21213231541 its reverse (14513231212), we get a palindrome (35726462753).

The spelling of 21213231541 in words is "twenty-one billion, two hundred thirteen million, two hundred thirty-one thousand, five hundred forty-one".