21553797 has 8 divisors (see below), whose sum is σ = 28766944. Its totient is φ = 14354928.

The previous prime is 21553789. The next prime is 21553837. The reversal of 21553797 is 79735512.

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

It is not a de Polignac number, because 21553797 - 2³ = 21553789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553717) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 678 + ... + 6600.

It is an arithmetic number, because the mean of its divisors is an integer number (3595868).

Almost surely, 2^21553797 is an apocalyptic number.

It is an amenable number.

21553797 is a deficient number, since it is larger than the sum of its proper divisors (7213147).

21553797 is a wasteful number, since it uses less digits than its factorization.

21553797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7139.

The product of its digits is 66150, while the sum is 39.

The square root of 21553797 is about 4642.6067031356. The cubic root of 21553797 is about 278.2966185172.

The spelling of 21553797 in words is "twenty-one million, five hundred fifty-three thousand, seven hundred ninety-seven".