16909978 has 8 divisors (see below), whose sum is σ = 25382772. Its totient is φ = 8449056.

The previous prime is 16909969. The next prime is 16909979. The reversal of 16909978 is 87990961.

It can be written as a sum of positive squares in 2 ways, for example, as 15737089 + 1172889 = 3967^2 + 1083^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (16909979) 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, 2976 + ... + 6532.

Almost surely, 2^16909978 is an apocalyptic number.

16909978 is a deficient number, since it is larger than the sum of its proper divisors (8472794).

16909978 is a wasteful number, since it uses less digits than its factorization.

16909978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5936.

The product of its (nonzero) digits is 244944, while the sum is 49.

The square root of 16909978 is about 4112.1743640074. The cubic root of 16909978 is about 256.6734890711.

The spelling of 16909978 in words is "sixteen million, nine hundred nine thousand, nine hundred seventy-eight".