21508774 has 16 divisors (see below), whose sum is σ = 39041568. Its totient is φ = 8675712.

The previous prime is 21508771. The next prime is 21508787. The reversal of 21508774 is 47780512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21508771) 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, 44949 + ... + 45424.

It is an arithmetic number, because the mean of its divisors is an integer number (2440098).

Almost surely, 2^21508774 is an apocalyptic number.

21508774 is a deficient number, since it is larger than the sum of its proper divisors (17532794).

21508774 is a wasteful number, since it uses less digits than its factorization.

21508774 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90399.

The product of its (nonzero) digits is 15680, while the sum is 34.

The square root of 21508774 is about 4637.7552759929. The cubic root of 21508774 is about 278.1027086288.

The spelling of 21508774 in words is "twenty-one million, five hundred eight thousand, seven hundred seventy-four".