21541493 has 2 divisors, whose sum is σ = 21541494. Its totient is φ = 21541492.

The previous prime is 21541477. The next prime is 21541517. The reversal of 21541493 is 39414512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12909649 + 8631844 = 3593^2 + 2938^2 .

It is a cyclic number.

It is not a de Polignac number, because 21541493 - 2⁴ = 21541477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21541423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770746 + 10770747.

It is an arithmetic number, because the mean of its divisors is an integer number (10770747).

Almost surely, 2^21541493 is an apocalyptic number.

It is an amenable number.

21541493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21541493 is an equidigital number, since it uses as much as digits as its factorization.

21541493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 29.

The square root of 21541493 is about 4641.2813963387. The cubic root of 21541493 is about 278.2436531648.

The spelling of 21541493 in words is "twenty-one million, five hundred forty-one thousand, four hundred ninety-three".