20742909 has 12 divisors (see below), whose sum is σ = 30400608. Its totient is φ = 12571240.

The previous prime is 20742901. The next prime is 20742919. The reversal of 20742909 is 90924702.

It is not a de Polignac number, because 20742909 - 2³ = 20742901 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a self number, because there is not a number n which added to its sum of digits gives 20742909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20742901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28209 + ... + 28934.

It is an arithmetic number, because the mean of its divisors is an integer number (2533384).

Almost surely, 2^20742909 is an apocalyptic number.

It is an amenable number.

20742909 is a deficient number, since it is larger than the sum of its proper divisors (9657699).

20742909 is a wasteful number, since it uses less digits than its factorization.

20742909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57168 (or 57157 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 20742909 is about 4554.4383846968. The cubic root of 20742909 is about 274.7619272888.

The spelling of 20742909 in words is "twenty million, seven hundred forty-two thousand, nine hundred nine".