20724947 has 4 divisors (see below), whose sum is σ = 20738640. Its totient is φ = 20711256.

The previous prime is 20724943. The next prime is 20724959. The reversal of 20724947 is 74942702.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20724947 - 2² = 20724943 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20724941) 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, 4247 + ... + 7712.

It is an arithmetic number, because the mean of its divisors is an integer number (5184660).

Almost surely, 2^20724947 is an apocalyptic number.

20724947 is a deficient number, since it is larger than the sum of its proper divisors (13693).

20724947 is a wasteful number, since it uses less digits than its factorization.

20724947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13692.

The product of its (nonzero) digits is 28224, while the sum is 35.

The square root of 20724947 is about 4552.4660350188. The cubic root of 20724947 is about 274.6825957774.

The spelling of 20724947 in words is "twenty million, seven hundred twenty-four thousand, nine hundred forty-seven".