20919397 has 4 divisors (see below), whose sum is σ = 21828960. Its totient is φ = 20009836.

The previous prime is 20919383. The next prime is 20919419. The reversal of 20919397 is 79391902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20919397 - 2¹¹ = 20917349 is a prime.

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 a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20919337) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 454747 + ... + 454792.

It is an arithmetic number, because the mean of its divisors is an integer number (5457240).

Almost surely, 2^20919397 is an apocalyptic number.

It is an amenable number.

20919397 is a deficient number, since it is larger than the sum of its proper divisors (909563).

20919397 is an equidigital number, since it uses as much as digits as its factorization.

20919397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909562.

The product of its (nonzero) digits is 30618, while the sum is 40.

The square root of 20919397 is about 4573.7727315642. The cubic root of 20919397 is about 275.5389848027.

It can be divided in two parts, 20919 and 397, that added together give a square (21316 = 146²).

The spelling of 20919397 in words is "twenty million, nine hundred nineteen thousand, three hundred ninety-seven".