21407994 has 12 divisors (see below), whose sum is σ = 46384026. Its totient is φ = 7135992.

The previous prime is 21407989. The next prime is 21407999. The reversal of 21407994 is 49970412.

It is an interprime number because it is at equal distance from previous prime (21407989) and next prime (21407999).

It can be written as a sum of positive squares in only one way, i.e., 20115225 + 1292769 = 4485^2 + 1137^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21407999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 594649 + ... + 594684.

Almost surely, 2^21407994 is an apocalyptic number.

21407994 is an abundant number, since it is smaller than the sum of its proper divisors (24976032).

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

21407994 is a wasteful number, since it uses less digits than its factorization.

21407994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1189341 (or 1189338 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21407994 is about 4626.8773487094. The cubic root of 21407994 is about 277.6676756300.

The spelling of 21407994 in words is "twenty-one million, four hundred seven thousand, nine hundred ninety-four".