21765427 has 2 divisors, whose sum is σ = 21765428. Its totient is φ = 21765426.

The previous prime is 21765421. The next prime is 21765437. The reversal of 21765427 is 72456712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21765427 - 2⁷ = 21765299 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21765392 and 21765401.

It is not a weakly prime, because it can be changed into another prime (21765421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882713 + 10882714.

It is an arithmetic number, because the mean of its divisors is an integer number (10882714).

Almost surely, 2^21765427 is an apocalyptic number.

21765427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765427 is an equidigital number, since it uses as much as digits as its factorization.

21765427 is an evil number, because the sum of its binary digits is even.

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

The square root of 21765427 is about 4665.3431813748. The cubic root of 21765427 is about 279.2044894572.

The spelling of 21765427 in words is "twenty-one million, seven hundred sixty-five thousand, four hundred twenty-seven".