21512047 has 8 divisors (see below), whose sum is σ = 23375360. Its totient is φ = 19721880.

The previous prime is 21512033. The next prime is 21512053. The reversal of 21512047 is 74021512.

It is a happy number.

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-21512047 is a prime.

It is a super-2 number, since 2×21512047² = 925536332260418, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17673 + ... + 18850.

It is an arithmetic number, because the mean of its divisors is an integer number (2921920).

Almost surely, 2^21512047 is an apocalyptic number.

21512047 is a deficient number, since it is larger than the sum of its proper divisors (1863313).

21512047 is a wasteful number, since it uses less digits than its factorization.

21512047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36573.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21512047 is about 4638.1081272433. The cubic root of 21512047 is about 278.1168142522.

Adding to 21512047 its reverse (74021512), we get a palindrome (95533559).

The spelling of 21512047 in words is "twenty-one million, five hundred twelve thousand, forty-seven".