21378937 has 8 divisors (see below), whose sum is σ = 22784256. Its totient is φ = 20013312.

The previous prime is 21378923. The next prime is 21378949. The reversal of 21378937 is 73987312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21378937 - 2¹¹ = 21376889 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21378937.

It is not an unprimeable number, because it can be changed into a prime (21378997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8808 + ... + 10969.

It is an arithmetic number, because the mean of its divisors is an integer number (2848032).

Almost surely, 2^21378937 is an apocalyptic number.

It is an amenable number.

21378937 is a deficient number, since it is larger than the sum of its proper divisors (1405319).

21378937 is a wasteful number, since it uses less digits than its factorization.

21378937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19847.

The product of its digits is 63504, while the sum is 40.

The square root of 21378937 is about 4623.7362597795. The cubic root of 21378937 is about 277.5419929417.

The spelling of 21378937 in words is "twenty-one million, three hundred seventy-eight thousand, nine hundred thirty-seven".