21101397 has 4 divisors (see below), whose sum is σ = 28135200. Its totient is φ = 14067596.

The previous prime is 21101383. The next prime is 21101401. The reversal of 21101397 is 79310112.

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 21101397 - 2²⁰ = 20052821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101317) 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, 3516897 + ... + 3516902.

It is an arithmetic number, because the mean of its divisors is an integer number (7033800).

Almost surely, 2^21101397 is an apocalyptic number.

It is an amenable number.

21101397 is a deficient number, since it is larger than the sum of its proper divisors (7033803).

21101397 is an equidigital number, since it uses as much as digits as its factorization.

21101397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7033802.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21101397 is about 4593.6256921957. The cubic root of 21101397 is about 276.3357471509.

The spelling of 21101397 in words is "twenty-one million, one hundred one thousand, three hundred ninety-seven".