21493901 has 32 divisors (see below), whose sum is σ = 26853120. Its totient is φ = 16934400.

The previous prime is 21493897. The next prime is 21493903. The reversal of 21493901 is 10939412.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21493901 - 2² = 21493897 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21493903) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 294401 + ... + 294473.

It is an arithmetic number, because the mean of its divisors is an integer number (839160).

Almost surely, 2^21493901 is an apocalyptic number.

It is an amenable number.

21493901 is a deficient number, since it is larger than the sum of its proper divisors (5359219).

21493901 is a wasteful number, since it uses less digits than its factorization.

21493901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 21493901 is about 4636.1515290163. The cubic root of 21493901 is about 278.0385925409.

The spelling of 21493901 in words is "twenty-one million, four hundred ninety-three thousand, nine hundred one".