20781968 has 40 divisors (see below), whose sum is σ = 41515200. Its totient is φ = 10074240.

The previous prime is 20781931. The next prime is 20782031. The reversal of 20781968 is 86918702.

20781968 = T₁₃₇ + T₁₃₈ + ... + T₅₀₂.

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, 104333 + ... + 104531.

It is an arithmetic number, because the mean of its divisors is an integer number (1037880).

Almost surely, 2^20781968 is an apocalyptic number.

It is an amenable number.

20781968 is a deficient number, since it is larger than the sum of its proper divisors (20733232).

20781968 is a wasteful number, since it uses less digits than its factorization.

20781968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375 (or 369 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 20781968 is about 4558.7243829826. The cubic root of 20781968 is about 274.9342785095.

The spelling of 20781968 in words is "twenty million, seven hundred eighty-one thousand, nine hundred sixty-eight".