21051518 has 4 divisors (see below), whose sum is σ = 31577280. Its totient is φ = 10525758.

The previous prime is 21051493. The next prime is 21051523. The reversal of 21051518 is 81515012.

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 = 21051493 and 21051502.

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, 5262878 + ... + 5262881.

It is an arithmetic number, because the mean of its divisors is an integer number (7894320).

Almost surely, 2^21051518 is an apocalyptic number.

21051518 is a deficient number, since it is larger than the sum of its proper divisors (10525762).

21051518 is a wasteful number, since it uses less digits than its factorization.

21051518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10525761.

The product of its (nonzero) digits is 400, while the sum is 23.

The square root of 21051518 is about 4588.1933263541. The cubic root of 21051518 is about 276.1178433272.

The spelling of 21051518 in words is "twenty-one million, fifty-one thousand, five hundred eighteen".