21971903 has 2 divisors, whose sum is σ = 21971904. Its totient is φ = 21971902.

The previous prime is 21971899. The next prime is 21971927. The reversal of 21971903 is 30917912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21971903 - 2² = 21971899 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21971903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21971933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10985951 + 10985952.

It is an arithmetic number, because the mean of its divisors is an integer number (10985952).

Almost surely, 2^21971903 is an apocalyptic number.

21971903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21971903 is an equidigital number, since it uses as much as digits as its factorization.

21971903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21971903 is about 4687.4196526447. The cubic root of 21971903 is about 280.0845960372.

The spelling of 21971903 in words is "twenty-one million, nine hundred seventy-one thousand, nine hundred three".