21124972 has 12 divisors (see below), whose sum is σ = 40329576. Its totient is φ = 9602240.

The previous prime is 21124969. The next prime is 21124973. The reversal of 21124972 is 27942112.

It is a self number, because there is not a number n which added to its sum of digits gives 21124972.

It is not an unprimeable number, because it can be changed into a prime (21124973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 240013 + ... + 240100.

It is an arithmetic number, because the mean of its divisors is an integer number (3360798).

Almost surely, 2^21124972 is an apocalyptic number.

21124972 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21124972 is a deficient number, since it is larger than the sum of its proper divisors (19204604).

21124972 is a wasteful number, since it uses less digits than its factorization.

21124972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480128 (or 480126 counting only the distinct ones).

The product of its digits is 2016, while the sum is 28.

The square root of 21124972 is about 4596.1910317131. The cubic root of 21124972 is about 276.4386185492.

The spelling of 21124972 in words is "twenty-one million, one hundred twenty-four thousand, nine hundred seventy-two".