21001072 has 10 divisors (see below), whose sum is σ = 40689608. Its totient is φ = 10500528.

The previous prime is 21001049. The next prime is 21001081. The reversal of 21001072 is 27010012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656268 + ... + 656299.

Almost surely, 2^21001072 is an apocalyptic number.

It is an amenable number.

21001072 is a deficient number, since it is larger than the sum of its proper divisors (19688536).

21001072 is a wasteful number, since it uses less digits than its factorization.

21001072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1312575 (or 1312569 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21001072 is about 4582.6926582524. The cubic root of 21001072 is about 275.8971121086.

Adding to 21001072 its reverse (27010012), we get a palindrome (48011084).

The spelling of 21001072 in words is "twenty-one million, one thousand, seventy-two".