991656478 has 16 divisors (see below), whose sum is σ = 1608496704. Its totient is φ = 456732160.

The previous prime is 991656469. The next prime is 991656487. The reversal of 991656478 is 874656199.

It is an interprime number because it is at equal distance from previous prime (991656469) and next prime (991656487).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 308683 + ... + 311878.

It is an arithmetic number, because the mean of its divisors is an integer number (100531044).

Almost surely, 2^991656478 is an apocalyptic number.

991656478 is a deficient number, since it is larger than the sum of its proper divisors (616840226).

991656478 is a wasteful number, since it uses less digits than its factorization.

991656478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620627.

The product of its digits is 3265920, while the sum is 55.

The square root of 991656478 is about 31490.5776066429. The cubic root of 991656478 is about 997.2110550169.

The spelling of 991656478 in words is "nine hundred ninety-one million, six hundred fifty-six thousand, four hundred seventy-eight".