21770087 has 2 divisors, whose sum is σ = 21770088. Its totient is φ = 21770086.

The previous prime is 21770059. The next prime is 21770093. The reversal of 21770087 is 78007712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21770087 - 2⁸ = 21769831 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21770017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885043 + 10885044.

It is an arithmetic number, because the mean of its divisors is an integer number (10885044).

Almost surely, 2^21770087 is an apocalyptic number.

21770087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21770087 is an equidigital number, since it uses as much as digits as its factorization.

21770087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5488, while the sum is 32.

The square root of 21770087 is about 4665.8425819995. The cubic root of 21770087 is about 279.2244140234.

Adding to 21770087 its reverse (78007712), we get a palindrome (99777799).

The spelling of 21770087 in words is "twenty-one million, seven hundred seventy thousand, eighty-seven".