21399774 has 16 divisors (see below), whose sum is σ = 46690560. Its totient is φ = 6484760.

The previous prime is 21399773. The next prime is 21399793. The reversal of 21399774 is 47799312.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21399773) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162054 + ... + 162185.

It is an arithmetic number, because the mean of its divisors is an integer number (2918160).

Almost surely, 2^21399774 is an apocalyptic number.

21399774 is an abundant number, since it is smaller than the sum of its proper divisors (25290786).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21399774 is a wasteful number, since it uses less digits than its factorization.

21399774 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324255.

The product of its digits is 95256, while the sum is 42.

The square root of 21399774 is about 4625.9889753435. The cubic root of 21399774 is about 277.6321325134.

The spelling of 21399774 in words is "twenty-one million, three hundred ninety-nine thousand, seven hundred seventy-four".