21571797 has 8 divisors (see below), whose sum is σ = 30974944. Its totient is φ = 13274928.

The previous prime is 21571763. The next prime is 21571801. The reversal of 21571797 is 79717512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21571797 - 2¹¹ = 21569749 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 553123 = 21571797 / (2 + 1 + 5 + 7 + 1 + 7 + 9 + 7).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571727) 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 7 ways as a sum of consecutive naturals, for example, 276523 + ... + 276600.

It is an arithmetic number, because the mean of its divisors is an integer number (3871868).

Almost surely, 2^21571797 is an apocalyptic number.

It is an amenable number.

21571797 is a deficient number, since it is larger than the sum of its proper divisors (9403147).

21571797 is a wasteful number, since it uses less digits than its factorization.

21571797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 553139.

The product of its digits is 30870, while the sum is 39.

The square root of 21571797 is about 4644.5448646773. The cubic root of 21571797 is about 278.3740672890.

The spelling of 21571797 in words is "twenty-one million, five hundred seventy-one thousand, seven hundred ninety-seven".