21980771 has 2 divisors, whose sum is σ = 21980772. Its totient is φ = 21980770.

The previous prime is 21980719. The next prime is 21980789. The reversal of 21980771 is 17708912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21980771 - 2¹⁴ = 21964387 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21980171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10990385 + 10990386.

It is an arithmetic number, because the mean of its divisors is an integer number (10990386).

Almost surely, 2^21980771 is an apocalyptic number.

21980771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21980771 is an equidigital number, since it uses as much as digits as its factorization.

21980771 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21980771 is about 4688.3654934316. The cubic root of 21980771 is about 280.1222722778.

The spelling of 21980771 in words is "twenty-one million, nine hundred eighty thousand, seven hundred seventy-one".