21499020 has 120 divisors (see below), whose sum is σ = 70497504. Its totient is φ = 5474304.

The previous prime is 21499003. The next prime is 21499021. The reversal of 21499020 is 2099412.

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

It is not an unprimeable number, because it can be changed into a prime (21499021) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 36972 + ... + 37548.

Almost surely, 2^21499020 is an apocalyptic number.

21499020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21499020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35248752).

21499020 is an abundant number, since it is smaller than the sum of its proper divisors (48998484).

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

21499020 is a wasteful number, since it uses less digits than its factorization.

21499020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621 (or 610 counting only the distinct ones).

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

The square root of 21499020 is about 4636.7035704259. The cubic root of 21499020 is about 278.0606634000.

The spelling of 21499020 in words is "twenty-one million, four hundred ninety-nine thousand, twenty".