21413918 has 4 divisors (see below), whose sum is σ = 32120880. Its totient is φ = 10706958.

The previous prime is 21413891. The next prime is 21413939. The reversal of 21413918 is 81931412.

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

It is a super-2 number, since 2×21413918² = 917111768221448, which contains 22 as substring.

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, 5353478 + ... + 5353481.

It is an arithmetic number, because the mean of its divisors is an integer number (8030220).

Almost surely, 2^21413918 is an apocalyptic number.

21413918 is a deficient number, since it is larger than the sum of its proper divisors (10706962).

21413918 is a wasteful number, since it uses less digits than its factorization.

21413918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10706961.

The product of its digits is 1728, while the sum is 29.

The square root of 21413918 is about 4627.5174770064. The cubic root of 21413918 is about 277.6932852474.

The spelling of 21413918 in words is "twenty-one million, four hundred thirteen thousand, nine hundred eighteen".