21357541 has 4 divisors (see below), whose sum is σ = 21854272. Its totient is φ = 20860812.

The previous prime is 21357529. The next prime is 21357563. The reversal of 21357541 is 14575312.

It is a happy number.

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 21357541 - 2⁵ = 21357509 is a prime.

It is a super-2 number, since 2×21357541² = 912289115133362, which 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 (21327541) 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, 248301 + ... + 248386.

It is an arithmetic number, because the mean of its divisors is an integer number (5463568).

Almost surely, 2^21357541 is an apocalyptic number.

It is an amenable number.

21357541 is a deficient number, since it is larger than the sum of its proper divisors (496731).

21357541 is an equidigital number, since it uses as much as digits as its factorization.

21357541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496730.

The product of its digits is 4200, while the sum is 28.

The square root of 21357541 is about 4621.4219673170. The cubic root of 21357541 is about 277.4493742021.

The spelling of 21357541 in words is "twenty-one million, three hundred fifty-seven thousand, five hundred forty-one".