81702021 has 16 divisors (see below), whose sum is σ = 112369664. Its totient is φ = 52771824.

The previous prime is 81702013. The next prime is 81702029. The reversal of 81702021 is 12020718.

It is an interprime number because it is at equal distance from previous prime (81702013) and next prime (81702029).

It is not a de Polignac number, because 81702021 - 2³ = 81702013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81702029) 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, 13890 + ... + 18876.

It is an arithmetic number, because the mean of its divisors is an integer number (7023104).

Almost surely, 2^81702021 is an apocalyptic number.

It is an amenable number.

81702021 is a deficient number, since it is larger than the sum of its proper divisors (30667643).

81702021 is a wasteful number, since it uses less digits than its factorization.

81702021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5160.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 81702021 is about 9038.9170258389. The cubic root of 81702021 is about 433.9212642177.

Adding to 81702021 its reverse (12020718), we get a palindrome (93722739).

The spelling of 81702021 in words is "eighty-one million, seven hundred two thousand, twenty-one".