21002245040 has 80 divisors (see below), whose sum is σ = 56003582208. Its totient is φ = 7175271168.

The previous prime is 21002245007. The next prime is 21002245073. The reversal of 21002245040 is 4054220012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21002245007) and next prime (21002245073).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92219 + ... + 224741.

Almost surely, 2^21002245040 is an apocalyptic number.

21002245040 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 21002245040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28001791104).

21002245040 is an abundant number, since it is smaller than the sum of its proper divisors (35001337168).

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

21002245040 is a wasteful number, since it uses less digits than its factorization.

21002245040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132826 (or 132820 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

Adding to 21002245040 its reverse (4054220012), we get a palindrome (25056465052).

The spelling of 21002245040 in words is "twenty-one billion, two million, two hundred forty-five thousand, forty".