21138097 has 4 divisors (see below), whose sum is σ = 21162816. Its totient is φ = 21113380.

The previous prime is 21138077. The next prime is 21138101. The reversal of 21138097 is 79083112.

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 a cyclic number.

It is not a de Polignac number, because 21138097 - 2²³ = 12749489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21138017) 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, 11029 + ... + 12802.

It is an arithmetic number, because the mean of its divisors is an integer number (5290704).

Almost surely, 2^21138097 is an apocalyptic number.

It is an amenable number.

21138097 is a deficient number, since it is larger than the sum of its proper divisors (24719).

21138097 is an equidigital number, since it uses as much as digits as its factorization.

21138097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24718.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21138097 is about 4597.6186227220. The cubic root of 21138097 is about 276.4958573740.

The spelling of 21138097 in words is "twenty-one million, one hundred thirty-eight thousand, ninety-seven".