30721987 has 2 divisors, whose sum is σ = 30721988. Its totient is φ = 30721986.

The previous prime is 30721969. The next prime is 30722051. The reversal of 30721987 is 78912703.

It is a weak prime.

It is an emirp because it is prime and its reverse (78912703) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 30721987 - 2¹¹ = 30719939 is a prime.

It is equal to p_1899901 and since 30721987 and 1899901 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (30721967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15360993 + 15360994.

It is an arithmetic number, because the mean of its divisors is an integer number (15360994).

Almost surely, 2^30721987 is an apocalyptic number.

30721987 is a deficient number, since it is larger than the sum of its proper divisors (1).

30721987 is an equidigital number, since it uses as much as digits as its factorization.

30721987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 30721987 is about 5542.7418305384. The cubic root of 30721987 is about 313.1961636149.

The spelling of 30721987 in words is "thirty million, seven hundred twenty-one thousand, nine hundred eighty-seven".