87721493 has 2 divisors, whose sum is σ = 87721494. Its totient is φ = 87721492.

The previous prime is 87721483. The next prime is 87721507. The reversal of 87721493 is 39412778.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85340644 + 2380849 = 9238^2 + 1543^2 .

It is a cyclic number.

It is not a de Polignac number, because 87721493 - 2¹² = 87717397 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 87721493.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87721453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43860746 + 43860747.

It is an arithmetic number, because the mean of its divisors is an integer number (43860747).

Almost surely, 2^87721493 is an apocalyptic number.

It is an amenable number.

87721493 is a deficient number, since it is larger than the sum of its proper divisors (1).

87721493 is an equidigital number, since it uses as much as digits as its factorization.

87721493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 41.

The square root of 87721493 is about 9365.9752829057. The cubic root of 87721493 is about 444.3262843225.

The spelling of 87721493 in words is "eighty-seven million, seven hundred twenty-one thousand, four hundred ninety-three".