21329490 has 96 divisors (see below), whose sum is σ = 63455616. Its totient is φ = 4492800.

The previous prime is 21329489. The next prime is 21329507. The reversal of 21329490 is 9492312.

21329490 = T₃₆ + T₃₇ + ... + T₅₀₃.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 35190 + ... + 35790.

It is an arithmetic number, because the mean of its divisors is an integer number (660996).

Almost surely, 2^21329490 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21329490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31727808).

21329490 is an abundant number, since it is smaller than the sum of its proper divisors (42126126).

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

21329490 is a wasteful number, since it uses less digits than its factorization.

21329490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644 (or 631 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21329490 is about 4618.3860817389. The cubic root of 21329490 is about 277.3278536244.

The spelling of 21329490 in words is "twenty-one million, three hundred twenty-nine thousand, four hundred ninety".