20978873 has 6 divisors (see below), whose sum is σ = 21436986. Its totient is φ = 20530352.

The previous prime is 20978863. The next prime is 20978887. The reversal of 20978873 is 37887902.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12759184 + 8219689 = 3572^2 + 2867^2 .

It is not a de Polignac number, because 20978873 - 2¹⁰ = 20977849 is a prime.

It is a super-2 number, since 2×20978873² = 880226224700258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978843) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2540 + ... + 6957.

It is an arithmetic number, because the mean of its divisors is an integer number (3572831).

Almost surely, 2^20978873 is an apocalyptic number.

It is an amenable number.

20978873 is a deficient number, since it is larger than the sum of its proper divisors (458113).

20978873 is an frugal number, since it uses more digits than its factorization.

20978873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9591 (or 9544 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 44.

The square root of 20978873 is about 4580.2699702092. The cubic root of 20978873 is about 275.7998662909.

The spelling of 20978873 in words is "twenty million, nine hundred seventy-eight thousand, eight hundred seventy-three".