21494951 has 4 divisors (see below), whose sum is σ = 21504552. Its totient is φ = 21485352.

The previous prime is 21494929. The next prime is 21494959. The reversal of 21494951 is 15949412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21494951 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 (21494959) 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, 536 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (5376138).

Almost surely, 2^21494951 is an apocalyptic number.

21494951 is a deficient number, since it is larger than the sum of its proper divisors (9601).

21494951 is an equidigital number, since it uses as much as digits as its factorization.

21494951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9600.

The product of its digits is 12960, while the sum is 35.

The square root of 21494951 is about 4636.2647681081. The cubic root of 21494951 is about 278.0431199612.

The spelling of 21494951 in words is "twenty-one million, four hundred ninety-four thousand, nine hundred fifty-one".