20638778 has 8 divisors (see below), whose sum is σ = 32025780. Its totient is φ = 9963520.

The previous prime is 20638771. The next prime is 20638789. The reversal of 20638778 is 87783602.

It can be written as a sum of positive squares in 2 ways, for example, as 18037009 + 2601769 = 4247^2 + 1613^2 .

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 (20638771) 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, 177863 + ... + 177978.

Almost surely, 2^20638778 is an apocalyptic number.

20638778 is a deficient number, since it is larger than the sum of its proper divisors (11387002).

20638778 is a wasteful number, since it uses less digits than its factorization.

20638778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355872.

The product of its (nonzero) digits is 112896, while the sum is 41.

The square root of 20638778 is about 4542.9921857736. The cubic root of 20638778 is about 274.3013804244.

The spelling of 20638778 in words is "twenty million, six hundred thirty-eight thousand, seven hundred seventy-eight".