20629681 has 4 divisors (see below), whose sum is σ = 20727664. Its totient is φ = 20531700.

The previous prime is 20629657. The next prime is 20629691. The reversal of 20629681 is 18692602.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18692602 = 2 ⋅9346301.

It is a cyclic number.

It is not a de Polignac number, because 20629681 - 2¹⁷ = 20498609 is a prime.

It is a super-2 number, since 2×20629681² = 851167476323522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20629621) 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, 48675 + ... + 49096.

It is an arithmetic number, because the mean of its divisors is an integer number (5181916).

Almost surely, 2^20629681 is an apocalyptic number.

It is an amenable number.

20629681 is a deficient number, since it is larger than the sum of its proper divisors (97983).

20629681 is an equidigital number, since it uses as much as digits as its factorization.

20629681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97982.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 20629681 is about 4541.9908630467. The cubic root of 20629681 is about 274.2610730256.

The spelling of 20629681 in words is "twenty million, six hundred twenty-nine thousand, six hundred eighty-one".