21507734 has 24 divisors (see below), whose sum is σ = 35223240. Its totient is φ = 9821952.

The previous prime is 21507709. The next prime is 21507743. The reversal of 21507734 is 43770512.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a junction number, because it is equal to n+sod(n) for n = 21507697 and 21507706.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 31622 + ... + 32294.

It is an arithmetic number, because the mean of its divisors is an integer number (1467635).

Almost surely, 2^21507734 is an apocalyptic number.

21507734 is a deficient number, since it is larger than the sum of its proper divisors (13715506).

21507734 is a wasteful number, since it uses less digits than its factorization.

21507734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 752 (or 723 counting only the distinct ones).

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

The square root of 21507734 is about 4637.6431514294. The cubic root of 21507734 is about 278.0982262490.

The spelling of 21507734 in words is "twenty-one million, five hundred seven thousand, seven hundred thirty-four".