21546949 has 4 divisors (see below), whose sum is σ = 21704364. Its totient is φ = 21389536.

The previous prime is 21546923. The next prime is 21546961. The reversal of 21546949 is 94964512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15069924 + 6477025 = 3882^2 + 2545^2 .

It is not a de Polignac number, because 21546949 - 2¹³ = 21538757 is a prime.

It is a super-2 number, since 2×21546949² = 928542022417202, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21546919) 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, 78502 + ... + 78775.

It is an arithmetic number, because the mean of its divisors is an integer number (5426091).

Almost surely, 2^21546949 is an apocalyptic number.

It is an amenable number.

21546949 is a deficient number, since it is larger than the sum of its proper divisors (157415).

21546949 is a wasteful number, since it uses less digits than its factorization.

21546949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157414.

The product of its digits is 77760, while the sum is 40.

The square root of 21546949 is about 4641.8691278406. The cubic root of 21546949 is about 278.2671422396.

The spelling of 21546949 in words is "twenty-one million, five hundred forty-six thousand, nine hundred forty-nine".