21542767 has 2 divisors, whose sum is σ = 21542768. Its totient is φ = 21542766.

The previous prime is 21542761. The next prime is 21542771. The reversal of 21542767 is 76724512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21542767 - 2⁷ = 21542639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771383 + 10771384.

It is an arithmetic number, because the mean of its divisors is an integer number (10771384).

Almost surely, 2^21542767 is an apocalyptic number.

21542767 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542767 is an equidigital number, since it uses as much as digits as its factorization.

21542767 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 34.

The square root of 21542767 is about 4641.4186408899. The cubic root of 21542767 is about 278.2491383220.

The spelling of 21542767 in words is "twenty-one million, five hundred forty-two thousand, seven hundred sixty-seven".