21881767 has 2 divisors, whose sum is σ = 21881768. Its totient is φ = 21881766.

The previous prime is 21881723. The next prime is 21881773. The reversal of 21881767 is 76718812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21881767 - 2¹⁵ = 21848999 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21881707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10940883 + 10940884.

It is an arithmetic number, because the mean of its divisors is an integer number (10940884).

Almost surely, 2^21881767 is an apocalyptic number.

21881767 is a deficient number, since it is larger than the sum of its proper divisors (1).

21881767 is an equidigital number, since it uses as much as digits as its factorization.

21881767 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37632, while the sum is 40.

The square root of 21881767 is about 4677.7951002582. The cubic root of 21881767 is about 279.7010712826.

The spelling of 21881767 in words is "twenty-one million, eight hundred eighty-one thousand, seven hundred sixty-seven".