15447991 has 4 divisors (see below), whose sum is σ = 16636312. Its totient is φ = 14259672.

The previous prime is 15447979. The next prime is 15448033. The reversal of 15447991 is 19974451.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19974451 = 7 ⋅2853493.

It is a cyclic number.

It is not a de Polignac number, because 15447991 - 2⁵ = 15447959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15447961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 594141 + ... + 594166.

It is an arithmetic number, because the mean of its divisors is an integer number (4159078).

Almost surely, 2^15447991 is an apocalyptic number.

15447991 is a deficient number, since it is larger than the sum of its proper divisors (1188321).

15447991 is a wasteful number, since it uses less digits than its factorization.

15447991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1188320.

The product of its digits is 45360, while the sum is 40.

The square root of 15447991 is about 3930.3932373237. The cubic root of 15447991 is about 249.0523644863.

The spelling of 15447991 in words is "fifteen million, four hundred forty-seven thousand, nine hundred ninety-one".