21619640 has 32 divisors (see below), whose sum is σ = 55594080. Its totient is φ = 7412352.

The previous prime is 21619621. The next prime is 21619649. The reversal of 21619640 is 4691612.

21619640 = T₄₂₁ + T₄₂₂ + ... + T₅₈₈.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21619649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38327 + ... + 38886.

It is an arithmetic number, because the mean of its divisors is an integer number (1737315).

Almost surely, 2^21619640 is an apocalyptic number.

21619640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21619640 is an abundant number, since it is smaller than the sum of its proper divisors (33974440).

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

21619640 is a wasteful number, since it uses less digits than its factorization.

21619640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77231 (or 77227 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21619640 is about 4649.6924629485. The cubic root of 21619640 is about 278.5797125992.

The spelling of 21619640 in words is "twenty-one million, six hundred nineteen thousand, six hundred forty".