21284972 has 12 divisors (see below), whose sum is σ = 38450496. Its totient is φ = 10299120.

The previous prime is 21284947. The next prime is 21284983. The reversal of 21284972 is 27948212.

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, 85703 + ... + 85950.

It is an arithmetic number, because the mean of its divisors is an integer number (3204208).

Almost surely, 2^21284972 is an apocalyptic number.

It is an amenable number.

21284972 is a deficient number, since it is larger than the sum of its proper divisors (17165524).

21284972 is a wasteful number, since it uses less digits than its factorization.

21284972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171688 (or 171686 counting only the distinct ones).

The product of its digits is 16128, while the sum is 35.

The square root of 21284972 is about 4613.5639152395. The cubic root of 21284972 is about 277.1347769534.

It can be divided in two parts, 212 and 84972, that added together give a cube (85184 = 44³).

The spelling of 21284972 in words is "twenty-one million, two hundred eighty-four thousand, nine hundred seventy-two".