21540807 has 12 divisors (see below), whose sum is σ = 31838664. Its totient is φ = 14026320.

The previous prime is 21540797. The next prime is 21540817. The reversal of 21540807 is 70804512.

It is an interprime number because it is at equal distance from previous prime (21540797) and next prime (21540817).

It is not a de Polignac number, because 21540807 - 2⁴ = 21540791 is a prime.

It is a super-2 number, since 2×21540807² = 928012732422498, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540817) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27444 + ... + 28217.

It is an arithmetic number, because the mean of its divisors is an integer number (2653222).

Almost surely, 2^21540807 is an apocalyptic number.

21540807 is a deficient number, since it is larger than the sum of its proper divisors (10297857).

21540807 is a wasteful number, since it uses less digits than its factorization.

21540807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55710 (or 55707 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21540807 is about 4641.2074937456. The cubic root of 21540807 is about 278.2406995291.

The spelling of 21540807 in words is "twenty-one million, five hundred forty thousand, eight hundred seven".