20870381 has 4 divisors (see below), whose sum is σ = 23851872. Its totient is φ = 17888892.

The previous prime is 20870371. The next prime is 20870389. The reversal of 20870381 is 18307802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-20870381 is a prime.

It is a super-2 number, since 2×20870381² = 871145606170322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20870389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1490735 + ... + 1490748.

It is an arithmetic number, because the mean of its divisors is an integer number (5962968).

Almost surely, 2^20870381 is an apocalyptic number.

It is an amenable number.

20870381 is a deficient number, since it is larger than the sum of its proper divisors (2981491).

20870381 is an equidigital number, since it uses as much as digits as its factorization.

20870381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2981490.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 20870381 is about 4568.4112117891. The cubic root of 20870381 is about 275.3236124209.

The spelling of 20870381 in words is "twenty million, eight hundred seventy thousand, three hundred eighty-one".