21512734 has 4 divisors (see below), whose sum is σ = 32269104. Its totient is φ = 10756366.

The previous prime is 21512719. The next prime is 21512747. The reversal of 21512734 is 43721512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21512699 and 21512708.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5378182 + ... + 5378185.

It is an arithmetic number, because the mean of its divisors is an integer number (8067276).

Almost surely, 2^21512734 is an apocalyptic number.

21512734 is a deficient number, since it is larger than the sum of its proper divisors (10756370).

21512734 is a wasteful number, since it uses less digits than its factorization.

21512734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10756369.

The product of its digits is 1680, while the sum is 25.

The square root of 21512734 is about 4638.1821870211. The cubic root of 21512734 is about 278.1197748292.

The spelling of 21512734 in words is "twenty-one million, five hundred twelve thousand, seven hundred thirty-four".