20651947 has 4 divisors (see below), whose sum is σ = 21002040. Its totient is φ = 20301856.

The previous prime is 20651933. The next prime is 20651959. The reversal of 20651947 is 74915602.

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 20651947 - 2⁷ = 20651819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20651047) 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, 174958 + ... + 175075.

It is an arithmetic number, because the mean of its divisors is an integer number (5250510).

Almost surely, 2^20651947 is an apocalyptic number.

20651947 is a deficient number, since it is larger than the sum of its proper divisors (350093).

20651947 is an equidigital number, since it uses as much as digits as its factorization.

20651947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350092.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 20651947 is about 4544.4413298006. The cubic root of 20651947 is about 274.3597092469.

The spelling of 20651947 in words is "twenty million, six hundred fifty-one thousand, nine hundred forty-seven".