21371406 has 32 divisors (see below), whose sum is σ = 49113600. Its totient is φ = 6073056.

The previous prime is 21371401. The next prime is 21371423. The reversal of 21371406 is 60417312.

It is a super-3 number, since 3×21371406³ (a number of 23 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21371401) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7080 + ... + 9636.

It is an arithmetic number, because the mean of its divisors is an integer number (1534800).

Almost surely, 2^21371406 is an apocalyptic number.

21371406 is an abundant number, since it is smaller than the sum of its proper divisors (27742194).

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

21371406 is a wasteful number, since it uses less digits than its factorization.

21371406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2768.

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21371406 is about 4622.9218033620. The cubic root of 21371406 is about 277.5093998926.

Adding to 21371406 its reverse (60417312), we get a palindrome (81788718).

The spelling of 21371406 in words is "twenty-one million, three hundred seventy-one thousand, four hundred six".