20699999 has 4 divisors (see below), whose sum is σ = 21917664. Its totient is φ = 19482336.

The previous prime is 20699993. The next prime is 20700011. The reversal of 20699999 is 99999602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99999602 = 2 ⋅49999801.

It is a cyclic number.

It is not a de Polignac number, because 20699999 - 2¹² = 20695903 is a prime.

It is a Duffinian number.

20699999 is a modest number, since divided by 9999 gives 2069 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20699999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20699993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 608807 + ... + 608840.

It is an arithmetic number, because the mean of its divisors is an integer number (5479416).

Almost surely, 2^20699999 is an apocalyptic number.

20699999 is a deficient number, since it is larger than the sum of its proper divisors (1217665).

20699999 is a wasteful number, since it uses less digits than its factorization.

20699999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1217664.

The product of its (nonzero) digits is 708588, while the sum is 53.

The square root of 20699999 is about 4549.7251565342. The cubic root of 20699999 is about 274.5723336063.

The spelling of 20699999 in words is "twenty million, six hundred ninety-nine thousand, nine hundred ninety-nine".