21164257541 has 4 divisors (see below), whose sum is σ = 24187722912. Its totient is φ = 18140792172.

The previous prime is 21164257537. The next prime is 21164257579. The reversal of 21164257541 is 14575246112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21164257541 - 2² = 21164257537 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21164257495 and 21164257504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164257531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1511732675 + ... + 1511732688.

It is an arithmetic number, because the mean of its divisors is an integer number (6046930728).

Almost surely, 2^21164257541 is an apocalyptic number.

It is an amenable number.

21164257541 is a deficient number, since it is larger than the sum of its proper divisors (3023465371).

21164257541 is an equidigital number, since it uses as much as digits as its factorization.

21164257541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3023465370.

The product of its digits is 67200, while the sum is 38.

The spelling of 21164257541 in words is "twenty-one billion, one hundred sixty-four million, two hundred fifty-seven thousand, five hundred forty-one".