21513051 has 12 divisors (see below), whose sum is σ = 35513712. Its totient is φ = 12293136.

The previous prime is 21513049. The next prime is 21513061. The reversal of 21513051 is 15031512.

It is not a de Polignac number, because 21513051 - 2¹ = 21513049 is a prime.

It is a super-2 number, since 2×21513051² = 925622726657202, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21513001) 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 11 ways as a sum of consecutive naturals, for example, 170676 + ... + 170801.

It is an arithmetic number, because the mean of its divisors is an integer number (2959476).

Almost surely, 2^21513051 is an apocalyptic number.

21513051 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21513051 is a deficient number, since it is larger than the sum of its proper divisors (14000661).

21513051 is a wasteful number, since it uses less digits than its factorization.

21513051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341490 (or 341487 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21513051 is about 4638.2163597659. The cubic root of 21513051 is about 278.1211408967.

Adding to 21513051 its reverse (15031512), we get a palindrome (36544563).

The spelling of 21513051 in words is "twenty-one million, five hundred thirteen thousand, fifty-one".