21420919 has 6 divisors (see below), whose sum is σ = 23195616. Its totient is φ = 19773000.

The previous prime is 21420887. The next prime is 21420941. The reversal of 21420919 is 91902412.

It is a happy number.

It is not a de Polignac number, because 21420919 - 2⁵ = 21420887 is a prime.

It is a super-2 number, since 2×21420919² = 917711541609122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420979) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 63207 + ... + 63544.

It is an arithmetic number, because the mean of its divisors is an integer number (3865936).

Almost surely, 2^21420919 is an apocalyptic number.

21420919 is a deficient number, since it is larger than the sum of its proper divisors (1774697).

21420919 is a wasteful number, since it uses less digits than its factorization.

21420919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126777 (or 126764 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21420919 is about 4628.2738683012. The cubic root of 21420919 is about 277.7235446774.

The spelling of 21420919 in words is "twenty-one million, four hundred twenty thousand, nine hundred nineteen".