21512983 has 4 divisors (see below), whose sum is σ = 22254840. Its totient is φ = 20771128.

The previous prime is 21512969. The next prime is 21513001. The reversal of 21512983 is 38921512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21512983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512483) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 370885 + ... + 370942.

It is an arithmetic number, because the mean of its divisors is an integer number (5563710).

Almost surely, 2^21512983 is an apocalyptic number.

21512983 is a deficient number, since it is larger than the sum of its proper divisors (741857).

21512983 is an equidigital number, since it uses as much as digits as its factorization.

21512983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 741856.

The product of its digits is 4320, while the sum is 31.

The square root of 21512983 is about 4638.2090293561. The cubic root of 21512983 is about 278.1208478613.

The spelling of 21512983 in words is "twenty-one million, five hundred twelve thousand, nine hundred eighty-three".