21731274 has 32 divisors (see below), whose sum is σ = 50394240. Its totient is φ = 6928416.

The previous prime is 21731273. The next prime is 21731291. The reversal of 21731274 is 47213712.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21731273) 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, 7507 + ... + 9990.

It is an arithmetic number, because the mean of its divisors is an integer number (1574820).

Almost surely, 2^21731274 is an apocalyptic number.

21731274 is an abundant number, since it is smaller than the sum of its proper divisors (28662966).

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

21731274 is a wasteful number, since it uses less digits than its factorization.

21731274 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17531 (or 17525 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21731274 is about 4661.6814562988. The cubic root of 21731274 is about 279.0583760379.

Adding to 21731274 its reverse (47213712), we get a palindrome (68944986).

The spelling of 21731274 in words is "twenty-one million, seven hundred thirty-one thousand, two hundred seventy-four".