21971489 has 2 divisors, whose sum is σ = 21971490. Its totient is φ = 21971488.

The previous prime is 21971483. The next prime is 21971501. The reversal of 21971489 is 98417912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17707264 + 4264225 = 4208^2 + 2065^2 .

It is a cyclic number.

It is not a de Polignac number, because 21971489 - 2¹⁶ = 21905953 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21971483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10985744 + 10985745.

It is an arithmetic number, because the mean of its divisors is an integer number (10985745).

Almost surely, 2^21971489 is an apocalyptic number.

It is an amenable number.

21971489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21971489 is an equidigital number, since it uses as much as digits as its factorization.

21971489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 41.

The square root of 21971489 is about 4687.3754916798. The cubic root of 21971489 is about 280.0828368852.

The spelling of 21971489 in words is "twenty-one million, nine hundred seventy-one thousand, four hundred eighty-nine".