21540737 has 8 divisors (see below), whose sum is σ = 23103360. Its totient is φ = 20021040.

The previous prime is 21540731. The next prime is 21540763. The reversal of 21540737 is 73704512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21540737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21540731) 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 7 ways as a sum of consecutive naturals, for example, 9689 + ... + 11702.

It is an arithmetic number, because the mean of its divisors is an integer number (2887920).

Almost surely, 2^21540737 is an apocalyptic number.

It is an amenable number.

21540737 is a deficient number, since it is larger than the sum of its proper divisors (1562623).

21540737 is a wasteful number, since it uses less digits than its factorization.

21540737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21463.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 21540737 is about 4641.1999525985. The cubic root of 21540737 is about 278.2403981341.

The spelling of 21540737 in words is "twenty-one million, five hundred forty thousand, seven hundred thirty-seven".