21378101 has 4 divisors (see below), whose sum is σ = 21391104. Its totient is φ = 21365100.

The previous prime is 21378083. The next prime is 21378107. The reversal of 21378101 is 10187312.

It is a happy number.

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 21378101 - 2¹⁰ = 21377077 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 (21378107) 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, 3605 + ... + 7466.

It is an arithmetic number, because the mean of its divisors is an integer number (5347776).

Almost surely, 2^21378101 is an apocalyptic number.

It is an amenable number.

21378101 is a deficient number, since it is larger than the sum of its proper divisors (13003).

21378101 is a wasteful number, since it uses less digits than its factorization.

21378101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13002.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21378101 is about 4623.6458558155. The cubic root of 21378101 is about 277.5383752356.

The spelling of 21378101 in words is "twenty-one million, three hundred seventy-eight thousand, one hundred one".