21976387 has 2 divisors, whose sum is σ = 21976388. Its totient is φ = 21976386.

The previous prime is 21976351. The next prime is 21976391. The reversal of 21976387 is 78367912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21976387 - 2¹⁵ = 21943619 is a prime.

It is not a weakly prime, because it can be changed into another prime (21976337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10988193 + 10988194.

It is an arithmetic number, because the mean of its divisors is an integer number (10988194).

Almost surely, 2^21976387 is an apocalyptic number.

21976387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21976387 is an equidigital number, since it uses as much as digits as its factorization.

21976387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127008, while the sum is 43.

The square root of 21976387 is about 4687.8979297762. The cubic root of 21976387 is about 280.1036478523.

The spelling of 21976387 in words is "twenty-one million, nine hundred seventy-six thousand, three hundred eighty-seven".