20747649 has 24 divisors (see below), whose sum is σ = 30989056. Its totient is φ = 12261600.

The previous prime is 20747647. The next prime is 20747653. The reversal of 20747649 is 94674702.

It is not a de Polignac number, because 20747649 - 2¹ = 20747647 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20747641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 158314 + ... + 158444.

Almost surely, 2^20747649 is an apocalyptic number.

It is an amenable number.

20747649 is a deficient number, since it is larger than the sum of its proper divisors (10241407).

20747649 is a wasteful number, since it uses less digits than its factorization.

20747649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309 (or 178 counting only the distinct ones).

The product of its (nonzero) digits is 84672, while the sum is 39.

The square root of 20747649 is about 4554.9587264870. The cubic root of 20747649 is about 274.7828544780.

The spelling of 20747649 in words is "twenty million, seven hundred forty-seven thousand, six hundred forty-nine".