20977906 has 4 divisors (see below), whose sum is σ = 31466862. Its totient is φ = 10488952.

The previous prime is 20977889. The next prime is 20977951. The reversal of 20977906 is 60977902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60977902 = 2 ⋅30488951.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 4372281 = 4075^2 + 2091^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5244475 + ... + 5244478.

Almost surely, 2^20977906 is an apocalyptic number.

20977906 is a deficient number, since it is larger than the sum of its proper divisors (10488956).

20977906 is a wasteful number, since it uses less digits than its factorization.

20977906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10488955.

The product of its (nonzero) digits is 47628, while the sum is 40.

The square root of 20977906 is about 4580.1644075295. The cubic root of 20977906 is about 275.7956286535.

The spelling of 20977906 in words is "twenty million, nine hundred seventy-seven thousand, nine hundred six".