21501943 has 2 divisors, whose sum is σ = 21501944. Its totient is φ = 21501942.

The previous prime is 21501929. The next prime is 21501967. The reversal of 21501943 is 34910512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21501943 - 2¹³ = 21493751 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21501913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750971 + 10750972.

It is an arithmetic number, because the mean of its divisors is an integer number (10750972).

Almost surely, 2^21501943 is an apocalyptic number.

21501943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21501943 is an equidigital number, since it uses as much as digits as its factorization.

21501943 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21501943 is about 4637.0187620927. The cubic root of 21501943 is about 278.0732645091.

The spelling of 21501943 in words is "twenty-one million, five hundred one thousand, nine hundred forty-three".