21290677 has 4 divisors (see below), whose sum is σ = 21300300. Its totient is φ = 21281056.

The previous prime is 21290653. The next prime is 21290693. The reversal of 21290677 is 77609212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 139876 + 21150801 = 374^2 + 4599^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21290677 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 (21290777) 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, 363 + ... + 6535.

It is an arithmetic number, because the mean of its divisors is an integer number (5325075).

Almost surely, 2^21290677 is an apocalyptic number.

It is an amenable number.

21290677 is a deficient number, since it is larger than the sum of its proper divisors (9623).

21290677 is an equidigital number, since it uses as much as digits as its factorization.

21290677 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9622.

The product of its (nonzero) digits is 10584, while the sum is 34.

The square root of 21290677 is about 4614.1821593864. The cubic root of 21290677 is about 277.1595348384.

Adding to 21290677 its reverse (77609212), we get a palindrome (98899889).

The spelling of 21290677 in words is "twenty-one million, two hundred ninety thousand, six hundred seventy-seven".