15721487 has 2 divisors, whose sum is σ = 15721488. Its totient is φ = 15721486.

The previous prime is 15721463. The next prime is 15721543. The reversal of 15721487 is 78412751.

It is a weak prime.

It is an emirp because it is prime and its reverse (78412751) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15721487 - 2⁶ = 15721423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15721427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7860743 + 7860744.

It is an arithmetic number, because the mean of its divisors is an integer number (7860744).

Almost surely, 2^15721487 is an apocalyptic number.

15721487 is a deficient number, since it is larger than the sum of its proper divisors (1).

15721487 is an equidigital number, since it uses as much as digits as its factorization.

15721487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15680, while the sum is 35.

The square root of 15721487 is about 3965.0330389544. The cubic root of 15721487 is about 250.5135417107.

The spelling of 15721487 in words is "fifteen million, seven hundred twenty-one thousand, four hundred eighty-seven".