20007978 has 8 divisors (see below), whose sum is σ = 40015968. Its totient is φ = 6669324.

The previous prime is 20007973. The next prime is 20007979. The reversal of 20007978 is 87970002.

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

20007978 is an admirable number.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (20007971) 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, 1667326 + ... + 1667337.

It is an arithmetic number, because the mean of its divisors is an integer number (5001996).

Almost surely, 2^20007978 is an apocalyptic number.

20007978 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20007978 is a wasteful number, since it uses less digits than its factorization.

20007978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3334668.

The product of its (nonzero) digits is 7056, while the sum is 33.

The square root of 20007978 is about 4473.0278335821. The cubic root of 20007978 is about 271.4778495677.

The spelling of 20007978 in words is "twenty million, seven thousand, nine hundred seventy-eight".