21619494 has 96 divisors (see below), whose sum is σ = 54812160. Its totient is φ = 6301152.

The previous prime is 21619489. The next prime is 21619501. The reversal of 21619494 is 49491612.

It is a happy number.

21619494 is a `hidden beast` number, since 2 + 161 + 9 + 494 = 666.

Its product of digits (15552) is a multiple of the sum of its prime divisors (144).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 209847 + ... + 209949.

It is an arithmetic number, because the mean of its divisors is an integer number (570960).

Almost surely, 2^21619494 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21619494, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27406080).

21619494 is an abundant number, since it is smaller than the sum of its proper divisors (33192666).

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

21619494 is a wasteful number, since it uses less digits than its factorization.

21619494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163 (or 144 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21619494 is about 4649.6767629589. The cubic root of 21619494 is about 278.5790855038.

It can be divided in two parts, 216 and 19494, that multiplied together give a square (4210704 = 2052²).

The spelling of 21619494 in words is "twenty-one million, six hundred nineteen thousand, four hundred ninety-four".