20947151 has 4 divisors (see below), whose sum is σ = 20963904. Its totient is φ = 20930400.

The previous prime is 20947141. The next prime is 20947153. The reversal of 20947151 is 15174902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15174902 = 2 ⋅7587451.

It is a cyclic number.

It is not a de Polignac number, because 20947151 - 2¹⁰ = 20946127 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 (20947153) 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, 6335 + ... + 9056.

It is an arithmetic number, because the mean of its divisors is an integer number (5240976).

Almost surely, 2^20947151 is an apocalyptic number.

20947151 is a deficient number, since it is larger than the sum of its proper divisors (16753).

20947151 is a wasteful number, since it uses less digits than its factorization.

20947151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16752.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 20947151 is about 4576.8057638488. The cubic root of 20947151 is about 275.6607845141.

The spelling of 20947151 in words is "twenty million, nine hundred forty-seven thousand, one hundred fifty-one".