21978053 has 4 divisors (see below), whose sum is σ = 21999360. Its totient is φ = 21956748.

The previous prime is 21978049. The next prime is 21978067. The reversal of 21978053 is 35087912.

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 21978053 - 2² = 21978049 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 (21978023) 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, 9023 + ... + 11196.

It is an arithmetic number, because the mean of its divisors is an integer number (5499840).

Almost surely, 2^21978053 is an apocalyptic number.

It is an amenable number.

21978053 is a deficient number, since it is larger than the sum of its proper divisors (21307).

21978053 is a wasteful number, since it uses less digits than its factorization.

21978053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21306.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 21978053 is about 4688.0756179908. The cubic root of 21978053 is about 280.1107257656.

The spelling of 21978053 in words is "twenty-one million, nine hundred seventy-eight thousand, fifty-three".