21799858 has 4 divisors (see below), whose sum is σ = 32699790. Its totient is φ = 10899928.

The previous prime is 21799849. The next prime is 21799871. The reversal of 21799858 is 85899712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 17164449 + 4635409 = 4143^2 + 2153^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5449963 + ... + 5449966.

Almost surely, 2^21799858 is an apocalyptic number.

21799858 is a deficient number, since it is larger than the sum of its proper divisors (10899932).

21799858 is a wasteful number, since it uses less digits than its factorization.

21799858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10899931.

The product of its digits is 362880, while the sum is 49.

The square root of 21799858 is about 4669.0318054175. The cubic root of 21799858 is about 279.3516375788.

The spelling of 21799858 in words is "twenty-one million, seven hundred ninety-nine thousand, eight hundred fifty-eight".