21248951 has 4 divisors (see below), whose sum is σ = 21548304. Its totient is φ = 20949600.

The previous prime is 21248921. The next prime is 21248957. The reversal of 21248951 is 15984212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21248951 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 (21248957) 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, 149570 + ... + 149711.

It is an arithmetic number, because the mean of its divisors is an integer number (5387076).

Almost surely, 2^21248951 is an apocalyptic number.

21248951 is a deficient number, since it is larger than the sum of its proper divisors (299353).

21248951 is an equidigital number, since it uses as much as digits as its factorization.

21248951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299352.

The product of its digits is 5760, while the sum is 32.

The square root of 21248951 is about 4609.6584472171. The cubic root of 21248951 is about 276.9783550360.

The spelling of 21248951 in words is "twenty-one million, two hundred forty-eight thousand, nine hundred fifty-one".