21401968 has 20 divisors (see below), whose sum is σ = 47390320. Its totient is φ = 9172224.

The previous prime is 21401957. The next prime is 21401987. The reversal of 21401968 is 86910412.

It is a happy number.

It is a congruent number.

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, 95433 + ... + 95656.

It is an arithmetic number, because the mean of its divisors is an integer number (2369516).

Almost surely, 2^21401968 is an apocalyptic number.

21401968 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21401968 is an abundant number, since it is smaller than the sum of its proper divisors (25988352).

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

21401968 is a wasteful number, since it uses less digits than its factorization.

21401968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191104 (or 191098 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 21401968 is about 4626.2261077470. The cubic root of 21401968 is about 277.6416202161.

The spelling of 21401968 in words is "twenty-one million, four hundred one thousand, nine hundred sixty-eight".