20921490 has 80 divisors (see below), whose sum is σ = 58753728. Its totient is φ = 5331744.

The previous prime is 20921479. The next prime is 20921501. The reversal of 20921490 is 9412902.

It is an interprime number because it is at equal distance from previous prime (20921479) and next prime (20921501).

It is a Harshad number since it is a multiple of its sum of digits (27).

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 39 ways as a sum of consecutive naturals, for example, 18069 + ... + 19191.

Almost surely, 2^20921490 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20921490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29376864).

20921490 is an abundant number, since it is smaller than the sum of its proper divisors (37832238).

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

20921490 is a wasteful number, since it uses less digits than its factorization.

20921490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1165 (or 1156 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 20921490 is about 4574.0015303889. The cubic root of 20921490 is about 275.5481737843.

The spelling of 20921490 in words is "twenty million, nine hundred twenty-one thousand, four hundred ninety".