20978722 has 4 divisors (see below), whose sum is σ = 31468086. Its totient is φ = 10489360.

The previous prime is 20978719. The next prime is 20978729. The reversal of 20978722 is 22787902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 22787902 = 2 ⋅11393951.

It can be written as a sum of positive squares in only one way, i.e., 20894041 + 84681 = 4571^2 + 291^2 .

It is not an unprimeable number, because it can be changed into a prime (20978729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5244679 + ... + 5244682.

Almost surely, 2^20978722 is an apocalyptic number.

20978722 is a deficient number, since it is larger than the sum of its proper divisors (10489364).

20978722 is a wasteful number, since it uses less digits than its factorization.

20978722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10489363.

The product of its (nonzero) digits is 28224, while the sum is 37.

The square root of 20978722 is about 4580.2534864350. The cubic root of 20978722 is about 275.7992045794.

The spelling of 20978722 in words is "twenty million, nine hundred seventy-eight thousand, seven hundred twenty-two".