21205077 has 8 divisors (see below), whose sum is σ = 28963200. Its totient is φ = 13791840.

The previous prime is 21205049. The next prime is 21205099. The reversal of 21205077 is 77050212.

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

It is not a de Polignac number, because 21205077 - 2⁷ = 21204949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205027) 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, 86077 + ... + 86322.

It is an arithmetic number, because the mean of its divisors is an integer number (3620400).

Almost surely, 2^21205077 is an apocalyptic number.

It is an amenable number.

21205077 is a deficient number, since it is larger than the sum of its proper divisors (7758123).

21205077 is a wasteful number, since it uses less digits than its factorization.

21205077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172443.

The product of its (nonzero) digits is 980, while the sum is 24.

The square root of 21205077 is about 4604.8970672535. The cubic root of 21205077 is about 276.7875923373.

Adding to 21205077 its reverse (77050212), we get a palindrome (98255289).

The spelling of 21205077 in words is "twenty-one million, two hundred five thousand, seventy-seven".