20729978 has 4 divisors (see below), whose sum is σ = 31094970. Its totient is φ = 10364988.

The previous prime is 20729939. The next prime is 20729981. The reversal of 20729978 is 87992702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 169 = 4553^2 + 13^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5182493 + ... + 5182496.

Almost surely, 2^20729978 is an apocalyptic number.

20729978 is a deficient number, since it is larger than the sum of its proper divisors (10364992).

20729978 is a wasteful number, since it uses less digits than its factorization.

20729978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10364991.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 20729978 is about 4553.0185591539. The cubic root of 20729978 is about 274.7048204636.

The spelling of 20729978 in words is "twenty million, seven hundred twenty-nine thousand, nine hundred seventy-eight".