21975287 has 2 divisors, whose sum is σ = 21975288. Its totient is φ = 21975286.

The previous prime is 21975167. The next prime is 21975307. The reversal of 21975287 is 78257912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21975287 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21975487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10987643 + 10987644.

It is an arithmetic number, because the mean of its divisors is an integer number (10987644).

Almost surely, 2^21975287 is an apocalyptic number.

21975287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21975287 is an equidigital number, since it uses as much as digits as its factorization.

21975287 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 70560, while the sum is 41.

The square root of 21975287 is about 4687.7806049345. The cubic root of 21975287 is about 280.0989743642.

The spelling of 21975287 in words is "twenty-one million, nine hundred seventy-five thousand, two hundred eighty-seven".