21513946 has 16 divisors (see below), whose sum is σ = 33286176. Its totient is φ = 10421136.

The previous prime is 21513931. The next prime is 21513949. The reversal of 21513946 is 64931512.

It is not an unprimeable number, because it can be changed into a prime (21513949) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 22245 + ... + 23191.

It is an arithmetic number, because the mean of its divisors is an integer number (2080386).

Almost surely, 2^21513946 is an apocalyptic number.

21513946 is a deficient number, since it is larger than the sum of its proper divisors (11772230).

21513946 is a wasteful number, since it uses less digits than its factorization.

21513946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1293.

The product of its digits is 6480, while the sum is 31.

The square root of 21513946 is about 4638.3128398158. The cubic root of 21513946 is about 278.1249977023.

It can be divided in two parts, 215 and 13946, that added together give a square (14161 = 119²).

The spelling of 21513946 in words is "twenty-one million, five hundred thirteen thousand, nine hundred forty-six".