20978397 has 24 divisors (see below), whose sum is σ = 34201440. Its totient is φ = 12274080.

The previous prime is 20978393. The next prime is 20978401. The reversal of 20978397 is 79387902.

It is an interprime number because it is at equal distance from previous prime (20978393) and next prime (20978401).

It is not a de Polignac number, because 20978397 - 2² = 20978393 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 783 + ... + 6524.

It is an arithmetic number, because the mean of its divisors is an integer number (1425060).

Almost surely, 2^20978397 is an apocalyptic number.

It is an amenable number.

20978397 is a deficient number, since it is larger than the sum of its proper divisors (13223043).

20978397 is a wasteful number, since it uses less digits than its factorization.

20978397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7353 (or 7350 counting only the distinct ones).

The product of its (nonzero) digits is 190512, while the sum is 45.

The square root of 20978397 is about 4580.2180079119. The cubic root of 20978397 is about 275.7977803553.

It can be divided in two parts, 209 and 78397, that added together give a triangular number (78606 = T₃₉₆).

The spelling of 20978397 in words is "twenty million, nine hundred seventy-eight thousand, three hundred ninety-seven".