21450778 has 8 divisors (see below), whose sum is σ = 33285780. Its totient is φ = 10355520.

The previous prime is 21450763. The next prime is 21450797. The reversal of 21450778 is 87705412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21187609 + 263169 = 4603^2 + 513^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 184863 + ... + 184978.

Almost surely, 2^21450778 is an apocalyptic number.

21450778 is a deficient number, since it is larger than the sum of its proper divisors (11835002).

21450778 is a wasteful number, since it uses less digits than its factorization.

21450778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369872.

The product of its (nonzero) digits is 15680, while the sum is 34.

The square root of 21450778 is about 4631.4984616212. The cubic root of 21450778 is about 277.8525260291.

The spelling of 21450778 in words is "twenty-one million, four hundred fifty thousand, seven hundred seventy-eight".