20791978 has 8 divisors (see below), whose sum is σ = 31253472. Its totient is φ = 10374156.

The previous prime is 20791973. The next prime is 20791987. The reversal of 20791978 is 87919702.

It is a happy number.

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 (20791973) 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, 9700 + ... + 11647.

It is an arithmetic number, because the mean of its divisors is an integer number (3906684).

Almost surely, 2^20791978 is an apocalyptic number.

20791978 is a deficient number, since it is larger than the sum of its proper divisors (10461494).

20791978 is a wasteful number, since it uses less digits than its factorization.

20791978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21836.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 20791978 is about 4559.8221456544. The cubic root of 20791978 is about 274.9784137326.

The spelling of 20791978 in words is "twenty million, seven hundred ninety-one thousand, nine hundred seventy-eight".