15951989 has 2 divisors, whose sum is σ = 15951990. Its totient is φ = 15951988.

The previous prime is 15951979. The next prime is 15951997. The reversal of 15951989 is 98915951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15665764 + 286225 = 3958^2 + 535^2 .

It is an emirp because it is prime and its reverse (98915951) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15951989 - 2⁴ = 15951973 is a prime.

It is a super-2 number, since 2×15951989² = 508931906112242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15951959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7975994 + 7975995.

It is an arithmetic number, because the mean of its divisors is an integer number (7975995).

Almost surely, 2^15951989 is an apocalyptic number.

It is an amenable number.

15951989 is a deficient number, since it is larger than the sum of its proper divisors (1).

15951989 is an equidigital number, since it uses as much as digits as its factorization.

15951989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145800, while the sum is 47.

The square root of 15951989 is about 3993.9941161699. The cubic root of 15951989 is about 251.7319155018.

Adding to 15951989 its sum of digits (47), we get a square (15952036 = 3994²).

The spelling of 15951989 in words is "fifteen million, nine hundred fifty-one thousand, nine hundred eighty-nine".