21072807 has 24 divisors (see below), whose sum is σ = 36301824. Its totient is φ = 11517264.

The previous prime is 21072769. The next prime is 21072823. The reversal of 21072807 is 70827012.

It is not a de Polignac number, because 21072807 - 2⁶ = 21072743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072827) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5823 + ... + 8720.

It is an arithmetic number, because the mean of its divisors is an integer number (1512576).

Almost surely, 2^21072807 is an apocalyptic number.

21072807 is a deficient number, since it is larger than the sum of its proper divisors (15229017).

21072807 is a wasteful number, since it uses less digits than its factorization.

21072807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14579 (or 14576 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 21072807 is about 4590.5127164621. The cubic root of 21072807 is about 276.2108895445.

Adding to 21072807 its reverse (70827012), we get a palindrome (91899819).

The spelling of 21072807 in words is "twenty-one million, seventy-two thousand, eight hundred seven".