20988739 has 4 divisors (see below), whose sum is σ = 20999160. Its totient is φ = 20978320.

The previous prime is 20988701. The next prime is 20988769. The reversal of 20988739 is 93788902.

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.

It is a cyclic number.

It is not a de Polignac number, because 20988739 - 2¹⁵ = 20955971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20988769) 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, 1117 + ... + 6574.

It is an arithmetic number, because the mean of its divisors is an integer number (5249790).

Almost surely, 2^20988739 is an apocalyptic number.

20988739 is a deficient number, since it is larger than the sum of its proper divisors (10421).

20988739 is an equidigital number, since it uses as much as digits as its factorization.

20988739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10420.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 20988739 is about 4581.3468543650. The cubic root of 20988739 is about 275.8430941458.

The spelling of 20988739 in words is "twenty million, nine hundred eighty-eight thousand, seven hundred thirty-nine".