21137797 has 2 divisors, whose sum is σ = 21137798. Its totient is φ = 21137796.

The previous prime is 21137777. The next prime is 21137801. The reversal of 21137797 is 79773112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21077281 + 60516 = 4591^2 + 246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21137797 - 2²³ = 12749189 is a prime.

It is a super-3 number, since 3×21137797³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21137707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10568898 + 10568899.

It is an arithmetic number, because the mean of its divisors is an integer number (10568899).

Almost surely, 2^21137797 is an apocalyptic number.

It is an amenable number.

21137797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21137797 is an equidigital number, since it uses as much as digits as its factorization.

21137797 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18522, while the sum is 37.

The square root of 21137797 is about 4597.5859970206. The cubic root of 21137797 is about 276.4945493226.

The spelling of 21137797 in words is "twenty-one million, one hundred thirty-seven thousand, seven hundred ninety-seven".