21007737 has 12 divisors (see below), whose sum is σ = 30384640. Its totient is φ = 13986648.

The previous prime is 21007709. The next prime is 21007741. The reversal of 21007737 is 73770012.

It is not a de Polignac number, because 21007737 - 2¹¹ = 21005689 is a prime.

It is a super-2 number, since 2×21007737² = 882650027722338, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21007737.

It is not an unprimeable number, because it can be changed into a prime (21007757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11064 + ... + 12822.

Almost surely, 2^21007737 is an apocalyptic number.

It is an amenable number.

21007737 is a deficient number, since it is larger than the sum of its proper divisors (9376903).

21007737 is a wasteful number, since it uses less digits than its factorization.

21007737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3092 (or 3089 counting only the distinct ones).

The product of its (nonzero) digits is 2058, while the sum is 27.

The square root of 21007737 is about 4583.4197931239. The cubic root of 21007737 is about 275.9262956943.

Adding to 21007737 its reverse (73770012), we get a palindrome (94777749).

The spelling of 21007737 in words is "twenty-one million, seven thousand, seven hundred thirty-seven".