20947557 has 8 divisors (see below), whose sum is σ = 29400160. Its totient is φ = 13230000.

The previous prime is 20947547. The next prime is 20947559. The reversal of 20947557 is 75574902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20947557 - 2⁷ = 20947429 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 (20947559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183694 + ... + 183807.

It is an arithmetic number, because the mean of its divisors is an integer number (3675020).

Almost surely, 2^20947557 is an apocalyptic number.

It is an amenable number.

20947557 is a deficient number, since it is larger than the sum of its proper divisors (8452603).

20947557 is a wasteful number, since it uses less digits than its factorization.

20947557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367523.

The product of its (nonzero) digits is 88200, while the sum is 39.

The square root of 20947557 is about 4576.8501177120. The cubic root of 20947557 is about 275.6625654652.

The spelling of 20947557 in words is "twenty million, nine hundred forty-seven thousand, five hundred fifty-seven".