1638977420 has 24 divisors (see below), whose sum is σ = 3515085504. Its totient is φ = 641641856.

The previous prime is 1638977407. The next prime is 1638977437. The reversal of 1638977420 is 247798361.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 870857 + ... + 872736.

It is an arithmetic number, because the mean of its divisors is an integer number (146461896).

Almost surely, 2^1638977420 is an apocalyptic number.

1638977420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1638977420 is an abundant number, since it is smaller than the sum of its proper divisors (1876108084).

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

1638977420 is a wasteful number, since it uses less digits than its factorization.

1638977420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1743649 (or 1743647 counting only the distinct ones).

The product of its (nonzero) digits is 508032, while the sum is 47.

The square root of 1638977420 is about 40484.2860873203. The cubic root of 1638977420 is about 1179.0285550608.

The spelling of 1638977420 in words is "one billion, six hundred thirty-eight million, nine hundred seventy-seven thousand, four hundred twenty".