20429640 has 288 divisors, whose sum is σ = 84651840. Its totient is φ = 4181760.

The previous prime is 20429627. The next prime is 20429657. The reversal of 20429640 is 4692402.

20429640 = T₅₇ + T₅₈ + ... + T₄₉₆.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 304887 + ... + 304953.

It is an arithmetic number, because the mean of its divisors is an integer number (293930).

Almost surely, 2^20429640 is an apocalyptic number.

20429640 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 20429640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42325920).

20429640 is an abundant number, since it is smaller than the sum of its proper divisors (64222200).

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

20429640 is a wasteful number, since it uses less digits than its factorization.

20429640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113 (or 95 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 20429640 is about 4519.9159284217. The cubic root of 20429640 is about 273.3717111821.

The spelling of 20429640 in words is "twenty million, four hundred twenty-nine thousand, six hundred forty".