21599997 has 8 divisors (see below), whose sum is σ = 28959840. Its totient is φ = 14320080.

The previous prime is 21599987. The next prime is 21600001. The reversal of 21599997 is 79999512.

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

It is not a de Polignac number, because 21599997 - 2⁶ = 21599933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21599957) 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, 19347 + ... + 20432.

It is an arithmetic number, because the mean of its divisors is an integer number (3619980).

Almost surely, 2^21599997 is an apocalyptic number.

It is an amenable number.

21599997 is a deficient number, since it is larger than the sum of its proper divisors (7359843).

21599997 is a wasteful number, since it uses less digits than its factorization.

21599997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39963.

The product of its digits is 459270, while the sum is 51.

The square root of 21599997 is about 4647.5796927003. The cubic root of 21599997 is about 278.4953171235.

The spelling of 21599997 in words is "twenty-one million, five hundred ninety-nine thousand, nine hundred ninety-seven".