87939721 has 2 divisors, whose sum is σ = 87939722. Its totient is φ = 87939720.

The previous prime is 87939707. The next prime is 87939727. The reversal of 87939721 is 12793978.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83466496 + 4473225 = 9136^2 + 2115^2 .

It is a cyclic number.

It is not a de Polignac number, because 87939721 - 2⁵ = 87939689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (87939727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43969860 + 43969861.

It is an arithmetic number, because the mean of its divisors is an integer number (43969861).

Almost surely, 2^87939721 is an apocalyptic number.

It is an amenable number.

87939721 is a deficient number, since it is larger than the sum of its proper divisors (1).

87939721 is an equidigital number, since it uses as much as digits as its factorization.

87939721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 190512, while the sum is 46.

The square root of 87939721 is about 9377.6180877662. The cubic root of 87939721 is about 444.6944348432.

The spelling of 87939721 in words is "eighty-seven million, nine hundred thirty-nine thousand, seven hundred twenty-one".