21547161 has 8 divisors (see below), whose sum is σ = 31921760. Its totient is φ = 14364756.

The previous prime is 21547157. The next prime is 21547187. The reversal of 21547161 is 16174512.

It is a happy number.

It is not a de Polignac number, because 21547161 - 2² = 21547157 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 798043 = 21547161 / (2 + 1 + 5 + 4 + 7 + 1 + 6 + 1).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21547111) 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, 398995 + ... + 399048.

It is an arithmetic number, because the mean of its divisors is an integer number (3990220).

Almost surely, 2^21547161 is an apocalyptic number.

It is an amenable number.

21547161 is a deficient number, since it is larger than the sum of its proper divisors (10374599).

21547161 is an equidigital number, since it uses as much as digits as its factorization.

21547161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798052 (or 798046 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 21547161 is about 4641.8919634132. The cubic root of 21547161 is about 278.2680548583.

The spelling of 21547161 in words is "twenty-one million, five hundred forty-seven thousand, one hundred sixty-one".