20699689 has 4 divisors (see below), whose sum is σ = 20710656. Its totient is φ = 20688724.

The previous prime is 20699671. The next prime is 20699713. The reversal of 20699689 is 98699602.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 98699602 = 2 ⋅49349801.

It is a cyclic number.

It is not a de Polignac number, because 20699689 - 2⁷ = 20699561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20699639) 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, 1849 + ... + 6694.

It is an arithmetic number, because the mean of its divisors is an integer number (5177664).

Almost surely, 2^20699689 is an apocalyptic number.

It is an amenable number.

20699689 is a deficient number, since it is larger than the sum of its proper divisors (10967).

20699689 is an equidigital number, since it uses as much as digits as its factorization.

20699689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10966.

The product of its (nonzero) digits is 419904, while the sum is 49.

The square root of 20699689 is about 4549.6910884147. The cubic root of 20699689 is about 274.5709629484.

The spelling of 20699689 in words is "twenty million, six hundred ninety-nine thousand, six hundred eighty-nine".