20739749 has 4 divisors (see below), whose sum is σ = 20749164. Its totient is φ = 20730336.

The previous prime is 20739731. The next prime is 20739769. The reversal of 20739749 is 94793702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 94793702 = 2 ⋅47396851.

It can be written as a sum of positive squares in 2 ways, for example, as 19518724 + 1221025 = 4418^2 + 1105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20739749 - 2⁸ = 20739493 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 (20739769) 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, 569 + ... + 6465.

It is an arithmetic number, because the mean of its divisors is an integer number (5187291).

Almost surely, 2^20739749 is an apocalyptic number.

It is an amenable number.

20739749 is a deficient number, since it is larger than the sum of its proper divisors (9415).

20739749 is an equidigital number, since it uses as much as digits as its factorization.

20739749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9414.

The product of its (nonzero) digits is 95256, while the sum is 41.

The square root of 20739749 is about 4554.0914571405. The cubic root of 20739749 is about 274.7479740581.

The spelling of 20739749 in words is "twenty million, seven hundred thirty-nine thousand, seven hundred forty-nine".