21599959 has 8 divisors (see below), whose sum is σ = 22050000. Its totient is φ = 21152832.

The previous prime is 21599957. The next prime is 21599987. The reversal of 21599959 is 95999512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21599959 - 2¹ = 21599957 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 (21599951) 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, 20067 + ... + 21115.

It is an arithmetic number, because the mean of its divisors is an integer number (2756250).

Almost surely, 2^21599959 is an apocalyptic number.

21599959 is a deficient number, since it is larger than the sum of its proper divisors (450041).

21599959 is a wasteful number, since it uses less digits than its factorization.

21599959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1457.

The product of its digits is 328050, while the sum is 49.

The square root of 21599959 is about 4647.5756045491. The cubic root of 21599959 is about 278.4951538082.

The spelling of 21599959 in words is "twenty-one million, five hundred ninety-nine thousand, nine hundred fifty-nine".