1021663540 has 24 divisors (see below), whose sum is σ = 2165181480. Its totient is φ = 404915328.

The previous prime is 1021663523. The next prime is 1021663549. The reversal of 1021663540 is 453661201.

It can be written as a sum of positive squares in 4 ways, for example, as 38464804 + 983198736 = 6202^2 + 31356^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1021663499 and 1021663508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021663549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 232147 + ... + 236506.

It is an arithmetic number, because the mean of its divisors is an integer number (90215895).

Almost surely, 2^1021663540 is an apocalyptic number.

1021663540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1021663540 is an abundant number, since it is smaller than the sum of its proper divisors (1143517940).

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

1021663540 is a wasteful number, since it uses less digits than its factorization.

1021663540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468771 (or 468769 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1021663540 is about 31963.4719641030. The cubic root of 1021663540 is about 1007.1696532232.

The spelling of 1021663540 in words is "one billion, twenty-one million, six hundred sixty-three thousand, five hundred forty".