21131077 has 6 divisors (see below), whose sum is σ = 23226854. Its totient is φ = 19209960.

The previous prime is 21131069. The next prime is 21131081. The reversal of 21131077 is 77013112.

It can be written as a sum of positive squares in only one way, i.e., 19945156 + 1185921 = 4466^2 + 1089^2 .

It is not a de Polignac number, because 21131077 - 2³ = 21131069 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 (21131087) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87198 + ... + 87439.

Almost surely, 2^21131077 is an apocalyptic number.

It is an amenable number.

21131077 is a deficient number, since it is larger than the sum of its proper divisors (2095777).

21131077 is a wasteful number, since it uses less digits than its factorization.

21131077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174659 (or 174648 counting only the distinct ones).

The product of its (nonzero) digits is 294, while the sum is 22.

The square root of 21131077 is about 4596.8551206232. The cubic root of 21131077 is about 276.4652457280.

Adding to 21131077 its reverse (77013112), we get a palindrome (98144189).

The spelling of 21131077 in words is "twenty-one million, one hundred thirty-one thousand, seventy-seven".