87742021 has 2 divisors, whose sum is σ = 87742022. Its totient is φ = 87742020.

The previous prime is 87742007. The next prime is 87742043. The reversal of 87742021 is 12024778.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62188996 + 25553025 = 7886^2 + 5055^2 .

It is a cyclic number.

It is not a de Polignac number, because 87742021 - 2⁷ = 87741893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87742001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43871010 + 43871011.

It is an arithmetic number, because the mean of its divisors is an integer number (43871011).

Almost surely, 2^87742021 is an apocalyptic number.

It is an amenable number.

87742021 is a deficient number, since it is larger than the sum of its proper divisors (1).

87742021 is an equidigital number, since it uses as much as digits as its factorization.

87742021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 87742021 is about 9367.0711004027. The cubic root of 87742021 is about 444.3609410459.

Adding to 87742021 its reverse (12024778), we get a palindrome (99766799).

The spelling of 87742021 in words is "eighty-seven million, seven hundred forty-two thousand, twenty-one".