21390733 has 16 divisors (see below), whose sum is σ = 26446336. Its totient is φ = 16848000.

The previous prime is 21390727. The next prime is 21390767. The reversal of 21390733 is 33709312.

It is not a de Polignac number, because 21390733 - 2²¹ = 19293581 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390793) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28108 + ... + 28858.

It is an arithmetic number, because the mean of its divisors is an integer number (1652896).

Almost surely, 2^21390733 is an apocalyptic number.

It is an amenable number.

21390733 is a deficient number, since it is larger than the sum of its proper divisors (5055603).

21390733 is a wasteful number, since it uses less digits than its factorization.

21390733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1084.

The product of its (nonzero) digits is 3402, while the sum is 28.

The square root of 21390733 is about 4625.0116756609. The cubic root of 21390733 is about 277.5930288967.

The spelling of 21390733 in words is "twenty-one million, three hundred ninety thousand, seven hundred thirty-three".