21930251 has 8 divisors (see below), whose sum is σ = 25100544. Its totient is φ = 18769320.

The previous prime is 21930157. The next prime is 21930269. The reversal of 21930251 is 15203912.

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

It is a cyclic number.

It is not a de Polignac number, because 21930251 - 2¹⁸ = 21668107 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21930281) 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 7 ways as a sum of consecutive naturals, for example, 3746 + ... + 7608.

It is an arithmetic number, because the mean of its divisors is an integer number (3137568).

Almost surely, 2^21930251 is an apocalyptic number.

21930251 is a deficient number, since it is larger than the sum of its proper divisors (3170293).

21930251 is an equidigital number, since it uses as much as digits as its factorization.

21930251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4681.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21930251 is about 4682.9745888698. The cubic root of 21930251 is about 279.9074992067.

The spelling of 21930251 in words is "twenty-one million, nine hundred thirty thousand, two hundred fifty-one".