21006502 has 16 divisors (see below), whose sum is σ = 34444800. Its totient is φ = 9528840.

The previous prime is 21006493. The next prime is 21006511. The reversal of 21006502 is 20560012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21006493) and next prime (21006511).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19699 + ... + 20737.

It is an arithmetic number, because the mean of its divisors is an integer number (2152800).

Almost surely, 2^21006502 is an apocalyptic number.

21006502 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21006502 is a deficient number, since it is larger than the sum of its proper divisors (13438298).

21006502 is a wasteful number, since it uses less digits than its factorization.

21006502 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1971.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21006502 is about 4583.2850664125. The cubic root of 21006502 is about 275.9208885491.

Adding to 21006502 its reverse (20560012), we get a palindrome (41566514).

The spelling of 21006502 in words is "twenty-one million, six thousand, five hundred two".