21690773 has 4 divisors (see below), whose sum is σ = 23359308. Its totient is φ = 20022240.

The previous prime is 21690743. The next prime is 21690787. The reversal of 21690773 is 37709612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10387729 + 11303044 = 3223^2 + 3362^2 .

It is a cyclic number.

It is not a de Polignac number, because 21690773 - 2¹⁰ = 21689749 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 (21690703) 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, 834248 + ... + 834273.

It is an arithmetic number, because the mean of its divisors is an integer number (5839827).

Almost surely, 2^21690773 is an apocalyptic number.

It is an amenable number.

21690773 is a deficient number, since it is larger than the sum of its proper divisors (1668535).

21690773 is a wasteful number, since it uses less digits than its factorization.

21690773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1668534.

The product of its (nonzero) digits is 15876, while the sum is 35.

The square root of 21690773 is about 4657.3353969840. The cubic root of 21690773 is about 278.8849060440.

The spelling of 21690773 in words is "twenty-one million, six hundred ninety thousand, seven hundred seventy-three".