21647994 has 8 divisors (see below), whose sum is σ = 43296000. Its totient is φ = 7215996.

The previous prime is 21647993. The next prime is 21648001. The reversal of 21647994 is 49974612.

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

21647994 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21647993) 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, 1803994 + ... + 1804005.

It is an arithmetic number, because the mean of its divisors is an integer number (5412000).

Almost surely, 2^21647994 is an apocalyptic number.

21647994 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21647994 is a wasteful number, since it uses less digits than its factorization.

21647994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3608004.

The product of its digits is 108864, while the sum is 42.

The square root of 21647994 is about 4652.7404827693. The cubic root of 21647994 is about 278.7014444842.

The spelling of 21647994 in words is "twenty-one million, six hundred forty-seven thousand, nine hundred ninety-four".