21137757 has 4 divisors (see below), whose sum is σ = 28183680. Its totient is φ = 14091836.

The previous prime is 21137741. The next prime is 21137773. The reversal of 21137757 is 75773112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21137741) and next prime (21137773).

It is a cyclic number.

It is not a de Polignac number, because 21137757 - 2⁴ = 21137741 is a prime.

It is a super-3 number, since 3×21137757³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21137707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3522957 + ... + 3522962.

It is an arithmetic number, because the mean of its divisors is an integer number (7045920).

Almost surely, 2^21137757 is an apocalyptic number.

It is an amenable number.

21137757 is a deficient number, since it is larger than the sum of its proper divisors (7045923).

21137757 is an equidigital number, since it uses as much as digits as its factorization.

21137757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7045922.

The product of its digits is 10290, while the sum is 33.

The square root of 21137757 is about 4597.5816469096. The cubic root of 21137757 is about 276.4943749149.

It can be divided in two parts, 2113 and 7757, that added together give a triangular number (9870 = T₁₄₀).

The spelling of 21137757 in words is "twenty-one million, one hundred thirty-seven thousand, seven hundred fifty-seven".