21179954 has 4 divisors (see below), whose sum is σ = 31769934. Its totient is φ = 10589976.

The previous prime is 21179911. The next prime is 21179959. The reversal of 21179954 is 45997112.

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

It can be written as a sum of positive squares in only one way, i.e., 18705625 + 2474329 = 4325^2 + 1573^2 .

It is not an unprimeable number, because it can be changed into a prime (21179959) 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 as a sum of consecutive naturals, namely, 5294987 + ... + 5294990.

Almost surely, 2^21179954 is an apocalyptic number.

21179954 is a deficient number, since it is larger than the sum of its proper divisors (10589980).

21179954 is a wasteful number, since it uses less digits than its factorization.

21179954 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10589979.

The product of its digits is 22680, while the sum is 38.

The square root of 21179954 is about 4602.1684019601. The cubic root of 21179954 is about 276.6782398668.

The spelling of 21179954 in words is "twenty-one million, one hundred seventy-nine thousand, nine hundred fifty-four".