21012099 has 8 divisors (see below), whose sum is σ = 28331280. Its totient is φ = 13850496.

The previous prime is 21012091. The next prime is 21012127. The reversal of 21012099 is 99021012.

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

It is not a de Polignac number, because 21012099 - 2³ = 21012091 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21012091) 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, 39082 + ... + 39615.

It is an arithmetic number, because the mean of its divisors is an integer number (3541410).

Almost surely, 2^21012099 is an apocalyptic number.

21012099 is a deficient number, since it is larger than the sum of its proper divisors (7319181).

21012099 is an equidigital number, since it uses as much as digits as its factorization.

21012099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78789.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 21012099 is about 4583.8956139947. The cubic root of 21012099 is about 275.9453919477.

It can be divided in two parts, 2 and 1012099, that added together give a palindrome (1012101).

The spelling of 21012099 in words is "twenty-one million, twelve thousand, ninety-nine".