20513640 has 64 divisors (see below), whose sum is σ = 70335360. Its totient is φ = 4688640.

The previous prime is 20513639. The next prime is 20513641. The reversal of 20513640 is 4631502.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20513639) and next prime (20513641).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (20513641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11371 + ... + 13050.

It is an arithmetic number, because the mean of its divisors is an integer number (1098990).

Almost surely, 2^20513640 is an apocalyptic number.

20513640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20513640 is an abundant number, since it is smaller than the sum of its proper divisors (49821720).

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

20513640 is a wasteful number, since it uses less digits than its factorization.

20513640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24442 (or 24438 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 20513640 is about 4529.1986046099. The cubic root of 20513640 is about 273.7458705409.

The spelling of 20513640 in words is "twenty million, five hundred thirteen thousand, six hundred forty".